Actors are essentially never seen in practice, but are traditionally Town-aligned.
This role is the inverse of the Priest.
A variant unofficially termed Sadist may only vote players who are at most three votes away from being lynched.
This is not to be confused with Hammerer.
Use and Power
Because it is usually impossible to prove a given player is an Actor if they only place hammering votes, the fact that this role is usually Town-aligned cannot be taken advantage of. However, the fact that Actor is a particularly unheard-of role makes it an unlikely falseclaim...
Ignoring the meta context, Actor is at best no different from Vanilla and at worst a distraction to the Town.