Faction or factionalism may refer to:
- Political faction, a group of people with a common political purpose
- The Faction, an American punk rock band
- Faction (Planescape), a political faction in the game Planescape
- Faction (literature), a type of historical novel based on fact
- Factions (Divergent)
- The Faction, an Atlanta United supporters' group
- Faction fighting, an English term for Irish mass stick fights, see Bataireacht
- a slang term for non-fiction novel (as a portmanteau of "fact" and "fiction")