Tommy's Group is a group of hostile survivors introduced in The Walking Dead: Rise of the Governor.
Nothing is known about the members of the group before the apocalypse, though judging by their appearance many of them were drug addicts. It's possible some members knew each other.
Early into the apocalypse, the group resorted to robbing and killing other survivors for their supplies.
The Peach Orchard
Having followed Philip Blake's group for fifty miles outside of Atlanta, Tommy and his group decided to attempt taking "The Peach Orchard" home away from Philip's group after doing a few days of scouting and recon with Blake's group inside. Having his men quickly round up Penny and Brian Blake, and Nick Parsons, a deal was struck while Philip was pointing an unloaded double-barrel shotgun at Tommy. The deal would allow Philip and his group to leave right then, at the cost of all of their possessions that were not on them at the moment. As Philip's group walked into the field unarmed, Tommy betrayed Philip and his men began hunting his group down. During the hunting that resulted, almost every member of his own group, including himself, were killed by either Philip or Nick (besides Sonny and Cher). Unfortunately, Penny Blake was also killed in the attack. As revenge for the death of his daughter, Philip tortures Sonny and Cher for days, while also raping the latter. They are put out of their misery by Nick when he discovers them.