People and things known as Jem include:

• Jem (singer), the stage name of the musician Jemma Griffiths
• Jem (TV series), a 1980s animated television series
• Jem (book), a 1980 book by Frederik Pohl
• a character in Harper Lee's To Kill a Mockingbird
• an Ibanez electric guitar designed by musician Steve Vai
• a nickname for James, Jeremiah or Jeremy

People and things known as JEM include:

• Justice and Equality Movement, a now defunct Sudanese rebel group
• Jaish-e-Mohammed, militant Islamist group based in Pakistan.
• The Journal of Environmental Monitoring
• The Journal of Experimental Medicine
• The Journal of Electronic Materials

See also: Gem and GEM