The Joker
With his green hair and permanent smile plastered on his face The Joker brings chaos and anarchy to Gotham city as Batman's arch enemy. This character was first introduced by DC (aka detective comics) in 1940 and still manages to captivate audiences today as seen in Christopher Nolan's "The Dark Knight." This character has been one of Batman's more predominant villains since his inception and is sure to be recognized among other Xbox 360 avatars as the famous clown prince of crime.
Mario
Mario first made his debut as Jumpman in the original "Donkey Kong" arcade game and has since become one of the most well known icons in gaming history. Throughout the decades Mario has starred in multiple games as well as been a cameo in others. These have included everything from Mario Kart all the way to "Super Smash Bros." This avatar will be recognized by nearly anyone in the gaming community as well as some who have no knowledge of video games at all.
Lara Croft
Lara Croft debuted on the original Sony Playstation in the video game "Tomb Raider." This character is an archaeologist and has been compared to a female version of Indiana Jones. Lara Croft is one of the first female characters to debut in the modern gaming world. Since the inception of the first "Tomb Raider" game, Lara Croft has been the star of multiple games in the series as well as two movies featuring the character.