Organizations
- Combine Empire (Half-Life)
- Black Mesa (Half-Life)
- The Resistance (Half-Life)
- Aperture Science (Portal)
- Xen (Half-Life)
Characters
Humans
- Gordon Freeman (Half-Life)
- Alyx Vance (Half-Life)
- Barney Calhoun (Half-Life)
- Eli Vance (Half-Life)
- Isaac Kleiner
- Judith Mossman
- G-Man (Half-Life)
- Chell (Portal)
- Wallace Breen (Half-Life)
- Cave Johnson (Portal)
Aliens
- Vortigaunt (Half-Life)
- Nihilanth (Half-Life)
Robots