| hint | name |
| Who you play as (duh!) | |
| A prominent figure in the human resistance | |
| A 22-year old U.S. Marine Corporal | |
| The playable character in Half-Life: Blue Shift | |
| A mysterious recurring character | |
| He makes up the core of the resistance | |
| His first appearance is in Half-Life: Decay | |
| He was never mentioned earlier in the series | |
| A robot dog | |
| | hint | name |
| A brilliant physicist and researcher | |
| First appears briefly in Red Letter Day | |
| A member of the Resistance | |
| A Russian Orthodox monk | |
| He was the administrator of Black Mesa | |
| The portal player character | |
| The robot in portal | |
| A dead billionaire and former Aperture Science CEO who had his mind placed inside a computer | |
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