The The Ancestors Character Pack Add-on for Assassin's Creed: Revelations has 4 achievements worth 90 gamerscore.
Obtain 3 Hidden Gun kills during a session of Steal The Artifact as The Corsair (Multiplayer).
Perform 5 Ground Finish in Manhunt during a session as The Brigand (Multiplayer).
Use the Bodyguard against your pursuer as The Privateer (Multiplayer).
Perform 3 kills using the Charge as The Gladiator (Multiplayer).