X1 or X-one may refer to:

• BMW X1, a 2009–present German subcompact luxury SUV
• Geely Yuanjing X1, a 2017–2021 Chinese mini crossover
• Red Bull X1, the former name of the Red Bull X2010, a fictional car created for the game Gran Turismo 5
• Wrightspeed X1, a 2008 electric sports car prototype based on the Ariel Atom

• X1 (Metrobus), a bus route in Washington, District of Columbia, United States
• X1 (New York City bus), a bus route in New York City, New York, United States
• X1 Steel Link, a bus rapid transit service between Sheffield, Rotherham, and Maltby in England, United Kingdom
• Excel X1, a bus route from Lowestoft to Peterborough in England, United Kingdom
• X1 Glasgow–Hamilton, a former bus route in Scotland
• Green Line routes X1 and X10, a former coach route from Southend-on-Sea to London

• SL X1, a former Swedish commuter train built by ASEA
• LNER Class X1, a single locomotive rebuilt several times in its history

• X1 (dinghy), a fast, light-weight sailing dinghy designed for inland racing
• HM Submarine X1, a Royal Navy submarine

• Bell X-1, an experimental rocket plane

• Sharp X1, a Japanese home computer manufactured by the Sharp Corporation
• Xbox One, a video game console
• a one-lane PCI Express slot
• Cray X1, a supercomputer sold since 2003
• Electrologica X1, an early Dutch computer
• Sony Ericsson XPERIA X1, a mobile phone
• ThinkPad X1 Carbon, a high-end notebook computer released by Lenovo in 2012
• X1 (software company) formerly known as X1 Technologies, Inc.
• Tegra X1, a system on a chip released by Nvidia in 2015
• X1, an IPTV-based cable television hardware platform developed by Comcast

• X1 (band), a South Korean boy band formed through Produce X 101
• X1 (rapper) (1979–2007), American rapper
• X Minus One, a 1950s American radio show
• X-Men (film), the first film in the X-Men franchise
• X-One, monthly magazine produced by Imagine Publishing

• x ⁻¹, the multiplicative inverse of x (another way to denote 1⁄x, one divided by x)
• United States patent X1, by Samuel Hopkins (inventor)
• X1 (Egyptian hieroglyph t), an extremely common alphabetic letter in the Ancient Egyptian alphabet
• X1, a former sister MMA promotion of the defunct Fighting of World Japan Pro Wrestling

• X-1 (disambiguation)
• 1X (disambiguation)