What Class Is the Drifter?

The Drifter has no class.

Is the drifter a warlock or hunter?

The Drifter is very old. He was reawakened by the Traveler in a mysterious time of great suffering known as the Dark Age, long before Guardians like the player were revived. He isn't a Hunter, Titan, or Warlock. He's a Lightbearer — a soul revived by the Traveler — from a different time.

Is the drifter Dredgen Yor?

That's a bit of a misnomer. He's called a Lightbearer in-game as he never joined up with the City, never helped surviving humans, etc. He lived in a time with Risen and Warlords, before the term “Guardian” was ever used. Can confirm: Drifter is NOT Dredgen Yor.