Bill Rizer, Lance Bean, Mad Dog, Scorpion. Yes, the "Contra guys" have names.
And don't go arguing about how original the character is--most of the Smash Bros. cast is like that.
They're way better than Nathan "Rad" Spencer, the titular Bionic Commando, anyway.
EDIT - But yeah, Simon would be first. I love Contra to death, but Castlevania's still the better, more iconic series. Even the music's like that: I love me some Contra tunes, but 'Vania has so much more potential in that area, especially considering how Smash Bros. handles classic music...
EDIT 2 - Fun Fact: Bill Rizer = Arnold Schwarzenegger, and Lance Bean = Sylvester Stallone. NOW YOU KNOW