Zachary Smith (or other forms such as Zac, Zach, Zack) may refer to:

• Armistead Burwell Smith IV, also known as Zach Smith, American rock musician with Three Mile Pilot and Pinback
• Zachary Smith (guitarist), American rock guitarist with The Loud Family, The Flying Monkeys, and Power13
• Zachary Dylan Smith (born 1994), American actor
• Zack Smith, American rock guitarist and songwriter with Scandal (American band)
• Zak Smith (born 1976), American artist and alternative porn star
• Zachary Cole Smith (born 1984), American musician, model and music video director

• Zac Smith (Shortland Street), a fictional character on the New Zealand soap opera Shortland Street
• Zacharias Smith, a fictional character from the Harry Potter books by J.K. Rowling
• Zachary Smith, a fictional character originated by Jonathan Harris on the TV series Lost in Space

• Zach "Hoeken" Smith, a co-founder of RepRap and MakerBot
• Zachary D. Smith (1990–2010), a U.S. Marine Lance Corporal killed in Afghanistan, memorialized by Zachary Smith Post Office
• Zachary Smith Reynolds (1911–1932), American amateur aviator and tobacco industry heir

• Zac Smith (born 1990), Australian-rules footballer
• Zack Smith (born 1988), Canadian ice hockey player
• Zach Smith (American football) (born 1998), American football quarterback

• Zachary Smith Post Office, in Hornell, New York