B-4
Data, Lore and B-4: the good, the bad and the retarded. B-4 is another android constructed by Doctor Noonien Soong. He appeared in the abomination Star Trek: Nemesis and is just as stupid as the film is.
He was found by the crew of the Enterprise-E in pieces on a pre-warp planet and taken back to the ship to be assembled.
After Picard and crew become acquainted with Shinzon, it is revealed that B-4 is part of the clone's master plan and tries to break into the Enterprise's computers. He is caught and Data takes his place in order to transport to the Scimitar to rescue Picard.
At the end of the film, following Data's destruction aboard the exploding Scimitar, it is hinted that Data's programming still flows in B-4's circuitry and that, like with Spock, Data may return from oblivion.