Greg may refer to:
- Greg (comics), the pen name of Belgian comic book artist Michel Regnier
- People
- Greg B. Abbott (1950), American businessperson, investor, entrepreneur and novelist
- Greg Camarillo, American football player with the Minnesota Vikings
- Greg Graffin, American punk rock musician, college professor, and author
- Greg Hoard, American journalist and sports commentator
- Gregg (surname), origin and list of people with the surnames Greg and Gregg
- People in fiction
- Dharma & Greg, an ABC situation comedy, starring Jenna Elfman and Thomas Gibson
- Greg the Bunny, puppet in a FOX situation comedy of the same name
- Greg Flemming, character in the webcomic User Friendly
- Greg House, protagonist of the FOX series, House, played by Hugh Laurie
- Greg Sanders, character in the CBS series CSI: Crime Scene Investigation, played by Eric Szmanda
- Greg Brady (Brady Bunch), character in The Brady Bunch, a popular 1970s TV show, played by Barry Williams
- Greg Heffley, protagonist of Diary of a Wimpy Kid
- Greg Warner, character in the CBS series yes, dear, played by Anthony Clark