Slammer can refer to:
- SQL Slammer, a Computer worm
- a slang term for prison or jail
- an "Alabama Slammer" or "Tequila Slammer" cocktail
- Sholef / Slammer, an Israeli self-propelled 155mm howitzer based on a Merkava tank chassis
- the non-transforming tank who is a partner to Metroplex in Transformers
- Slammer Guitars, a budget subsidiary of Hamer Guitars
- an AIM-120 AMRAAM Missile, nicknamed Slammer
- Penn Jillette's house in Las Vegas, also known as "the slammer"
- Slammer (calypsonian), an early Barbadian calypsonian
- Slammer (Ride), the second S&S Power Sky Swat in the world at Thorpe Park, Surrey, England
- Slammer, an entity who changes a telephone carrier of a telephone line illegally (Telephone slamming)
- Railfan term for a British Rail electrical multiple unit based on Mark 1 carriages, having manual doors that one has to slam, hence the term.
- A type of POG