Sarah Knuckey Marrow
Sarah Knuckey / Marrow. Textless variant cover of Realm of X #1 (August 2023). Art by Karen S. Darboe
Publication information
Publisher	Marvel Comics
First appearance	As Sarah Knuckey: Cable #15 (September 1994) As Marrow: X-Men Prime (July 1995)
Created by	Jeph Loeb (writer) David Brewer (artist)
In-story information
Alter ego	Sarah Knuckey[1]
Species	Human mutant
Team affiliations	Gene Nation S.H.I.E.L.D. Weapon X Morlocks X-Force X-Men
Notable aliases	Marrow, Sarah Rushman[2]
Abilities	Superhuman strength, stamina, durability, agility, reflexes, and tracking Controlled bone growth Healing factor Street fighting skills Weapon proficiency

Sarah Knuckey is a fictional character appearing in American comic books published by Marvel Comics. Created by writer Jeph Loeb and artist David Brewer, the character first appeared in Cable #15 (September 1994).^[3] Knuckey belongs to the subspecies of humans called mutants who are born with superhuman abilities.^[4] She is known under the codename Marrow.^[5] She is able to make her bones grow out of her skin.^[6] These can be removed from her body, providing her with potential knives, clubs, and body armor.^[7]

As a child, Knuckey was taken in by the Morlocks, a band of grotesque-looking mutants who hid in tunnels beneath New York City. As a young adult, she formed the violent splinter cell Gene Nation until, under the orders of Morlock leader Callisto, she joined the X-Men to redeem herself. She made progress controlling her powers and learning a moral code, but eventually fell in with the paramilitary group Weapon X.

Sarah Knuckey debuted in Cable #15 (September 1994),^[8] created by writer Jeph Loeb and artist David Brewer.^[9] She later appeared as Marrow in the 1995 X-Men Prime one-shot. She appeared in the 2000 Spidey/Marrow one-shot,^[10] the 2006 X-Factor series,^[11] and the 2019 Marauders series.^[12]

As a child, Sarah was one of the underground-dwelling Morlocks. During the Mutant Massacre that devastated the Morlock community, she witnessed the mauling of Angel by the Marauders. She was saved by Gambit, who was then not yet known by the X-Men. Years later, most of the surviving Morlocks (including Sarah) were apparently killed by Mikhail Rasputin, although they were actually brought to another dimension. There, Mikhail had established a citadel for himself on the top of a massive hill. The Social Darwinist philosophy of "survival of the fittest" was the only thing which governed the society. If someone could reach the summit of the hill, they were considered "fit" and worthy of being part of Gene Nation.

The former Morlock leader Callisto cared for Marrow during this period and displayed a maternal attitude towards the young mutant, although the two are not known to be biologically related. When her powers fully manifested, she was forced to "up the hill", becoming more savage and killing her opponents to survive. When she managed to reach the top, Mikhail considered her fit to join his elite fighting team Gene Nation, which eventually became a terrorist group whose mission was to punish humans for their hatred towards mutants.^{[volume & issue needed]}

In that harsh dimension, time passed quickly, and when Marrow and several other members of Gene Nation (of which she had become leader) returned to Earth, they discovered only a few years had passed during their absence. Marrow and the other members of Gene Nation began a homicidal terrorist campaign against surface-dwelling humans. After inconclusive battles with the X-Men and Generation X, Gene Nation was defeated by the X-Men. Marrow wired a time bomb to her own heart to force the X-Man Storm, who had herself led the Morlocks in the past, to either yield or kill her; Storm tore out Marrow's heart. However, due to Marrow's possession of two hearts to compensate for her random bone growth and superhuman regenerative abilities, she survived. Marrow eventually reunited with Callisto, and while they continued their terrorist activities, Callisto tried to hold back Marrow's more violent ways.^{[volume & issue needed]}

After a battle with Cable, Marrow and Callisto returned to seclusion. When Callisto was injured by a Prime Sentinel during the events of Operation: Zero Tolerance, she directed Marrow to seek the aid of the X-Men. After teaming up with Iceman and Cecilia Reyes, Marrow went to the Xavier Institute. She joined the X-Men for a time, coming under the mentorship of Wolverine and flirting with her teammate Cannonball. When the team came under the attack of the Shadow King, Marrow managed to resist when the Shadow King tempted and tortured her in an attempt to gain her loyalty. She also helped Cannonball resist by viciously destroying the illusion of his abusive father. Cannonball was shaken by seeing Marrow slay the illusion of his parent.^{[volume & issue needed]}

Marrow also participated in the fight against the returning N'Garai, extra-dimensional monsters who were loose on the grounds of the X-Mansion. She saved fellow X-Men Cecilia Reyes by impaling one of the creatures threatening her.^{[volume & issue needed]}

Around this time Marrow would confront Spider-Man, because both were interested in investigating a unique type of kidnapping. Eyewitnesses reported the victims literally dragged into the sewers, something which of course interested Marrow, because of her Morlock heritage. Investigating the disappearances, they discovered them to be the work of the vampire-like being known as Hunger, who was swiftly defeated in a confrontation with Spider-Man.^{[volume & issue needed]}

During an adventure in another dimension, Gambit, unable to control his powers, accidentally injured Marrow. She later traveled to the past with the X-Men, ending up on the Skrull homeworld a short time before the cosmic entity known as Galactus would destroy it. A medical device gave her more control over her powers, giving her a "prettier" appearance. The suspension-properties of a captured Skrull rescue ship allowed her and her fellow X-Men to make the journey back to Earth in real time, without aging at all. Thus, for a while, two Marrows existed in the time stream, one on Earth and one in space.^{[volume & issue needed]}

The change of her features led to major softening of her personality, to the point where she reached out to Jubilee following Wolverine's disappearance in the lead up to "The Twelve" storyline. She also tried to cheer up returning X-Man Colossus in a scheme involving his artwork and her storytelling.^{[volume & issue needed]}

Marrow left the X-Men during the six-month gap preceding the "X-Men Revolution", though her reasons for doing so are unclear.^{[volume & issue needed]}

She was next seen brainwashed by S.H.I.E.L.D. under the alias of "Sarah Rushman" used as a sleeper agent. Her mission was to terminate rogue Life Model Decoys. She had a split personality (mutant Marrow and human teenager Sarah) and had to be periodically injected to keep her implanted memory. With Spider-Man's help (he briefly dated her Sarah personality as Mary Jane was believed dead at this point), she freed herself from SHIELD's control by faking a suicide.^[2]

Marrow was later recruited by the most recent incarnation of Weapon X, who again normalized her appearance and her powers. However, she eventually betrayed Weapon X upon discovering their anti-mutant nature. She used the remnants of Cable's Underground to reform the Gene Nation terrorist group and, as their leader, led several terrorist attacks on Weapon X until the rest of the group was slaughtered by Agent Zero. Agent Zero left her alone, not wanting her to become a martyr, but he warned her that he would come after her again after he had hunted down the remaining members of Gene Nation.^{[volume & issue needed]}

Marrow was next seen as a spokeswoman of a band of Morlocks after M-Day. She gave an interview to Sally Floyd for her ex-mutant diaries. Marrow remains underground to protect and give hope to the few mutants who remain and those who fear going to the surface to live normal lives.^{[volume & issue needed]} Mike Marts, editor for the X-Men comic books, confirmed in an interview that although Sarah retains some of the physical attributes of her mutation, her actual mutant powers disappeared during Decimation.^[13]

Marrow later turns up as a member of X-Cell, a terrorist group of former mutants believing that M-Day was caused by the U.S. government. As part of X-Cell, Marrow fought M and Siryn of X-Factor Investigations and after a turn of events in which she and Callisto learned the truth about who is responsible for M-Day, she turned against X-Cell supporter Quicksilver. Both heavily injured each other with a knife wound during the fight. Afterwards, she and Callisto managed to escape X-Factor and the government through the sewers.^[14]

In Feb. 2014, Marrow returns as a member of a new X-Force team, along with a semblance of her powers intact. After some examination from Doctor Nemesis, Marrow is revealed to be not a mutant.^[15] It has since been revealed that Marrow wasn't abducted at all. She willingly approached Volga, the one responsible for giving former mutants their powers back, for an experimental procedure to restore her power. At this point Marrow was already pregnant and despite the great risks this posed for her child, she accepted. The procedure was successful, and Marrow's powers were restored at the cost of her child, and she was left for dead in Alexandria during the Alexandria Incident.^[16] She was eventually found by Cable, who provided her with an inhibitor collar built by Doctor Nemesis to suppress her memories and control her powers.^[17]

In the Secret Empire storyline, Marrow is affiliated with New Tian and fights along other mutants.^[18] Afterwards, Sarah joins Magneto's new Brotherhood of Mutants. She and others under his service attack an anti-mutant rally in Washington DC.^[19] Some time later she appears at a self-help group therapy session for mutants who suffered from debilitating appearances due to their abilities.^[20]

After a massive reality distorting event caused by X-Man had left much of the mutant population decimated once again, Marrow and a couple of other mutants work with Emma Frost as debutantes in her new Hellfire Club.^[21] But they are soon beset by the O.N.E., now under command of the bigoted and corrupt Robert Callahan as part of his campaign of registering, incarcerating and modifying mutants for the purpose of exterminating other mutants. The duplicitous director coerces the Black King into tracking other mutants for his minions to round up in his government sanctioned facilities while under threat of execution. But Emma works with Marrow the others to contact the last remaining X-Men to deal with the O.N.E.^[22]

Somewhere later down the line; after the new mutant nation of Krakoa was established and declared its independence upon the world stage, Professor X offers amnesty to all of mutant kind in the form of an invite to their personal island nation.^[23] Even the more socially abrasive amongst Homo Superior are welcomed amongst their growing numbers, as Marrow could be seen amongst an enclave of villainous mutants who accepted his summons. She is now a duly recognized citizen of the mutant nation.^[24]

Sarah Knuckey possesses the ability to enhance the growth of her skeletal structure.^[25] She uses her power in many ways, including the creation of knuckle guards, spears, and projectile spikes.^[26] She also has a healing factor and enhanced immune system, much in the same vein as Wolverine since every time a bone is ripped out a wound which remains closes itself soon after. Her bones seem to be much more durable than normal; she had easily survived heavy hits in multiple areas of her body. Flag-Smasher hit her twice on the head with his mace without much damage, and Sabretooth likewise threw her against a wall without harm. Knuckey also jumped off the Brooklyn Bridge twice (something that would have resulted in death or at least crippling injuries) without any major damage, being able to walk away from the scene. She possesses two hearts to compensate for her random bone growth as well, so when Storm ripped one out she was able to survive.^[27]

Knuckey is also more agile and stronger than the average woman in her age group and physical condition, and has excellent tracking skills.

Darren Franich of Entertainment Weekly stated Sarah Knuckey embodies "superhero body horror at its finest," saying Swiss artist Hans Ruedi Giger would have appreciated the character.^[28] Deirdre Kaye of Scary Mommy called Sarah Knuckey a "role model" and a "truly heroic" female character.^[29] Amer Sawan of Comic Book Resources noted the similarities between the powers of Sarah Knuckey and the newly-acquired abilities of Captain Boomerang from DC Comics.^[30]

Sarah Knuckey placed 8th in a popularity contest held by Marvel Comics in 2021,^[31] which served to determine who would be the final member of a new X-Men team that would debut during the Hellfire Gala storyline.^[32]

An alternate version of Sarah Knuckey appears in X-Men: Age of Apocalypse. She makes a brief appearance in the second issue of the limited series, as a member of the Morlocks, a group of mutants who were victims of Sinister's experiments.^[33]

An alternate version of Sarah Knuckey appears in the "House of M" storyline. She is a member of the Red Guard whose mission is to capture or eliminate the Hood's gang in Santa Rico. Sarah helped Rogue in killing the Sandman only to be shot down by the Hood.^[34]

An alternate version of Sarah Knuckey appears in the alternate reality depicted in the "Age of X" storyline. She possessed her powers. Whether she retained them after being returned to Reality-616 with the X-Men and other mutants remains to be seen.^[35]

An alternate version of Sarah Knuckey appears in Ultimate X-Men. She is killed by Mister Sinister acting on orders from Apocalypse.^[36]

• Marrow appears in Wolverine and the X-Men, voiced by Tara Strong. This version is a member of Charles Xavier's future X-Men who hails from a post-apocalyptic, Sentinel-controlled future and initially doubts his leadership. After befriending and losing a reprogrammed Sentinel she had nicknamed "Rover", she secretly helps the Sentinels to spite Xavier until her teammates get caught in the crossfire and the Sentinels betray her. Afterward, she and Polaris help Xavier defeat Master Mold.
• Marrow makes a cameo appearance in the X-Men '97 episode "Remember It" as a resident of Genosha who is later killed by Sentinels.^[37][38][39]

Marrow makes a cameo appearance in Deadpool as a patient of an underground facility called the Workshop.^[40][41]

• Marrow appears as a playable character in Marvel vs. Capcom 2: New Age of Heroes, voiced by Susan Hart.^[42]
• Marrow makes a cameo appearance in Ultimate Marvel vs. Capcom 3.^{[citation needed]}
• Marrow appears as a boss in X-Men Legends, voiced by Nancy Linari.^[43] This version is the leader of the Gene Nation. She initially works with the Brotherhood of Mutants until she learns they do not care about her or her allies.

In 1995, Toy Biz released a Marrow action figure as part of the "X-Men Generation X" line.^[44][45]

• Marrow at Marvel.com