Heavy and Bomb are two Badniks created by Dr. Eggman that appear in the Sega 32X game, Knuckles' Chaotix. For unknown reasons, these two robots defected from the doctor and helped Knuckles and the Chaotix to destroy Eggman's Carnival Island. They have never appeared in any games since then, though they have appeared in the Sonic Archie comics.
Heavy's body is made in the shape of a coffee pot and is seemingly indestructable. He is immune to spike traps and Badnik attacks and can destroy them upon touch. His main weakness is his weight (as his name implies) which makes him slower than the other Chaotix characters and unable to jump very high. However, when partnered with Charmy Bee (so long as Charmy's the leader) he can be quite handy as he becomes a destructive wrecking ball while Charmy's in flight.
A small red and black bomb robot with arms and legs. Bomb is practically the opposite of Heavy: he is light, fast, can jump to a reasonable height and is very, very destructible. Bomb will explode if touched by an enemy, damaging whatever and whoever is within his blast radius, including allies. He will regenerate shortly after exploding.
Heavy and Bomb first appear in Archie Comics' Sonic Chaotix tie-in special, helping the patrons of Happyland Amusement Park escape from Dr. Robotnik's clutches. In this version, Heavy has more of a barrel-shaped body and Bomb does not regenerate, instead new Bombs are produced inside Heavy's body. After the tie-in special, Heavy and Bomb disappeared, but would reappear some time after the First Robotnik War ended, volunteering to become members of King Acorn's Secret Service under Geoffrey St. John. However, when Dr. Eggman returned to Mobius, Heavy and Bomb were captured and reprogrammed. They returned to Knothole as the doctor's sleeper agents, going berserk once they were inside Castle Acorn. Heavy produced numerous Bombs and attempted to assassinate the royal family, but was destroyed by Sonic the Hedgehog.
During the Second Robotnik War, Dr. Eggman built a new Heavy and Bomb to assassinate Mina Mongoose, a former Freedom Fighter who had become a singer (and Eggman REALLY hated her music). This plot was foiled by Sonic and the two Badniks were destroyed.
Recently, a new Heavy and Bomb duo has appeared within New Mobotropolis, created by Rotor Walrus and Tails. They function as members of the new "Team Freedom" that has been established to take care of any threats to the city.