Some alternatives, in rough descending order of innoffensiveness:

Nazi.
Stalinist.
Mussolini-ite.
Franco-ist.
McCarthy-ite.
Duplessi National Unionist.
Thatcherite.
Reaganite.
Mulroney-ite.
My Brother-in-Law-ite.
Dickhead.
Jerk.

Cranky vegetarians are, on this scale, Food-Thatcherites.