9. Madd Dog & OG Loc
Rockstar could have bent to fan pressure and brought back any number of former GTA protagonists, but their approach to paying homage to their lineage of characters was far more smart. We of course have Niko Bellic featured on the Life Invader website (and his cousin Roman as a contact, which will be somewhat odd for players who chose to let the side-kick die in GTA IV) and other protagonists also pop up in unexpected places (more of which later.) Madd Dog and OG Loc from San Andreas are probably the most difficult cameos to spot - mostly because they don't actually appear in person - though their spirits are preserved in the game thanks to their music. Despite the fact that both are shown as losers in San Andreas (Madd Dog mostly because Loc ruined his career for a while, and Loc because his rapping was attrocious) the gap between the games has obviously been kind to both. They're both famous enough to have their own albums, both of which can be found in Franklin's apartment and both have their own stars on the Vinewood Walk of Fame.
How To Find Them Scope around in Franklins apartment for the CDs, and North Vinewood for the Vinewood Hall Of Fame.