In Mass Effect 3 for the PC, PS3, and Xbox 360, you can unlock the Salarian Engineer as a character to use in multiplayer, which is an agile support character.
The Salarian Engineer is an uncommon card that you can get from purchasing any of the packs. Your chances are typically better to unlock characters by purchasing Veteran and Spectre packs instead of Recruit packs though.
Check out my other guide for more unlockable characters in Mass Effect 3 multiplayer.