Legion Legion Laches Legion can refer to several encyclopedic topics, including:

In Military history, an organization or military unit:
- A Roman legion.
- A Polish Legion.
- A Foreign legion.
- The American Legion
- The Czech Legion
In Bible studies:
- Legion (demon), a demon mentioned in the Gospel of Mark.
In Computer science:
- Legion (model), a computer programming model.
- Legion (software), a software package.
In comic books:
- Legion, an X-Men villain.
- The Legion of Super-Heroes, a DC Comics superhero team.
- L.E.G.I.O.N., a DC Comics title.
- Legion, a Green Lantern villain.