Popeye - Will Forte
Will Forte should really be a bigger name. Currently, I hear him as regular voice on Allen Gregory... that is, if the show hasn't been cancelled yet.
Olive Oyl
Sarah Silverman was almost too obvious.
Bluto - Alec Baldwin
Alec Baldwin is the toughest comedic actor I could think of. The man is a chameleon! I currently watch him on 30 Rock.
Wimpy - Nick Offerman
Nick Offerman is an under-rated actor who is finally getting his due in Parks & Recreation.