Jammer may refer to:
- Jammer keyboard
- Jammer, a device used in radar jamming and deception and Communications System Jamming, a technique in electronic warfare to inhibit or halt the transmission of signals
- Mobile phone jammer, an instrument used to prevent cellular phones from receiving signals from base stations.
- Swim jammer, a type of male competitive swimwear
- Max Jammer, a noted physicist in the 20th century
- Jammer (Battlestar Galactica), a character in the TV series Battlestar Galactica
- The red buses used to shuttle guests around Glacier National Park
- Jammer (mascot), mascot of the Northern League Joliet Jackhammers
- A player for the Jamestown Jammers minor league baseball team
- Jammer, the scoring position in Roller derby
- Quentin Jammer, a cornerback for the San Diego Chargers
- Jammer (rapper), a UK grime MC
- Jammer (Jammer Direct), a member of the Social Networking Site Jammer Direct
- Jammers, a group of characters in the TV series The Prisoner who use misdirection to confuse onlookers with misinformation
- Jammer (Sailing), a mechanical fitting with a lever arm that cleats a rope.
- Um Jammer Lammy, a rhythm video game for the PSX
- Jammer (Artist,Host), a copyrighted artist and co-host of "The Spit or Swallow Beer Review" with Shagdog from www.mytrurevu.com and on YouTube channel named "mytrurevu"