18. Red Harlow
As Red Dead Revolver was the real first instalment in the series (making the original Red Dead Redemption its 'part two'), Red Dead Redemption 2's title makes no sense, but Revolver's protagonist is still referenced by countless actors.
Stumble onto any camp site or saloon, and travellers will regale you in the tale of one Red Harlow. He doesn't actually appear to be in the game, sadly, but considering how big RDR2 is, it may be wise to not rule him out yet.