Mario, Link, Pac, Lara?
Mario, Link, Lara, Cloud?
Mario, Link, Lara, Wander?
Mario, Link, Wander, Gordon?
Edit: Sonic may be recognizable from cross-marketing but his quality is dubious. He's been in four good games.
Mario saved gaming and is the industry's most iconic figure.
Lara invigorated gaming's jump to 3D (even if Mario stuck the landing).
Pac was the earliest superstar even if that star has faded since the 1980's.
Donkey Kong and Pikachu are an early and an ongoing fixture but it's just too much Nintendo.
Wander is among the earliest "Games are art" protagonists and a contender for best game ever made.
Gordon Freeman is PC Gaming's champion and a contender for best game of all-time in his own right.