In Mass Effect 3 for the PC, PS3, and Xbox 360, you can unlock the Turian Soldier as a character to use in multiplayer, which is an powerful combat character with a larger health pool and the widest selection of weapons.
The Turian Soldier is an uncommon card that you can get from purchasing any of the packs, but your chances are much better to get characters by purchasing Veteran and Spectre packs instead of Recruit packs.
Check out my other guide for more unlockable characters in Mass Effect 3 multiplayer.