An interesting question. I tend to buy/categorize my movies more by genre rather than actor. I mean, I have the entire Friday The 13th franchise on DVD, but the actors change in every movie, even when the characters don't. I can try and list a few.
Arnold Schwarzenegger (Conan 1 & 2, Red Sonja)
Harrison Ford (Star Wars OT)
Ewan McGregor (Star Wars PT)
Samuel L Jackson (Star Wars PT)
Kane Hodder (Friday The 13th 7, 8, JGTH, and Jason X)
Dwayne "The Rock" Johnson (Scorpion King, Walking Tall, The Rundown, Faster)
Hulk Hogan (No Holds Barred, Mr Nanny, Suburban Commando)
If we include TV series Sara Michelle Gellar (Buffy Seasons 1 through 7)
Tom Welling (Smallville Seasons 1 through 5)
Christopher Lee (Attack Of The Clowns, Revenge Of The S#!t, and the LOTR Trilogy)
Jamie Lee Curtis (Halloween 1 & 2, Halloween: H20)
Before my Harry Potter collection was stolen, I would've added Warwick Davis (Willow, Return Of The Jedi, and the entire HP series)
That's all I can think of right now.