Left to right:

    Wander (Shadows of the Colossus)
    KOS-MOS (Xenosaga)
    Ethan Mars (Heavy Rain) (Thanks to LFreeze!)
    The Illusive Man (Mass Effect) (Thanks to nodefect)
    Frame 1 - Professor Layton
    Master Chief with plasma grenade
    Frame 2 - Phoenix Wright
    Commander Shepard
    Alyx Vance
    Raz (Psychonauts)
    Glados (Portal)
    Andrew Ryan (Bioshock) (Corrected by Apothekerin)
    The Boss (MGS3) (Corrected by johndelfino)
    Nathan Drake (Uncharted)
    Tim (Braid)
    Elena Fisher (Uncharted) (Corrected by sweatyspaghetti)
    Ezio Auditore da Firenze
    Frame 3 - The King (Katamari Damacy)
    HK-47 (Star Wars KOTOR)
    John Marston (Red Dead Redemption) (Thanks to NOACeulemans!)
    Bonnie MacFarlane (Red Dead Redemption) (Thanks to NOACeulemans!)
    Jimmy Hopkins (Bully)
    Captain Price (Call of Duty) (Thanks to Dontkare)
    Kaim Argonar (Lost Odyssey)
    Teyrn Loghain (Dragon Age) (Thanks to ZapActions-dower)
    Kratos
    Tommy Vercetti (GTA: Vice City) (Thanks to NOACeulemans!)
    Niko Bellic (GTA 4)
    Jade (Beyond Good & Evil)
    Auron (FF X)