Nothing is known about Reilly's life prior to or as the outbreak began.
At some point in the apocalypse, Reilly somehow came into contact with a group named "The Saviors" which he subsequently joined.
Reilly and the other escaped Savior prisoners capture Rick and Morgan near the abandoned dive bar they are resting at. With injured comrades, the Saviors argue over what to do, particularly as Rick reveals that a herd is on the way. Jared refuses to believe them while insisting that they kill Rick and Morgan and press on to the Sanctuary. Rick offers the Saviors a chance to return to the Hilltop and join the community, in which Reilly and a few others seem to seriously consider Rick's offer.
As the herd attacks the bar, Evan and another Savior free Rick and Morgan. As Reilly provided cover fire for Rick and Morgan, he is suddenly attacked by Rick with a hatchet. He was bitten by the invading walkers as he was laying on the ground, dying. He speaks a few words to Rick, choking on his own blood. Rick shoots him once in the head with his revolver.
- Killed By
After Rick and Morgan are freed by Evan, Reilly provides cover fire for them, however, he is suddenly attacked by Rick with a hatchet.
As he lays on the ground, dying, he speaks a few words to Rick before being shot by him.
This list shows the victims Reilly has killed:
- Numerous counts of zombies and possibly unnamed people
- Reilly's first and only appearance was in "Still Gotta Mean Something". He, along with the other credited Saviors in this episode, was not credited nor did he appear in any other Season 8 episode featuring Alden and the other Savior prisoners.
- Reilly is the last named person that Rick Grimes killed before leaving the show.
- Rick approaching a badly-hurt Reilly and trying to listen to what he says before killing him is a reference to a similar event with Rick and Bob Lamson in "Coda".