Barret is the vulgar, 35 year old that creates Avalanche as a way to rebel against the Shinra Corporation.  His left hand was shot off in a struggle at North Corel, and so it is permanently transformed into a chain gun.  He takes care of Marlene along with Tifa, and I believe he sets a new record for having the most obscenities in a video game(at the time).  Note that him, along with Cid, are a reference towards the late Syd Barret of Pink Floyd.

Limit Breaks
Lv. 1: Big Shot-Barret creates a ball of energy on his arm cannon and fires it at the enemy.  For some reason, Big Shot sometimes does insane amounts of damage to incredibly weak amounts for me.
Mindblow-Does the exact same thing as Big Shot except it drains MP from the enemy.

Lv. 2: Grenade Bomb-Barret launches a grenade at the enemy, doing damage.
Hammer Blow-Does the exact same thing as Cloud's Finishing Touch, instantly killing an enemy target(ineffective against bosses).

Lv. 3: Satellite Beam-Barret locks on to every single enemy, and powerful satellite lasers are blasted at them, dealing huge damage.
Ungarmax-This is cool!  Barret takes aim, and just shoots the living hell out of the enemy, doing crazy damage.

Lv. 4: Catastrophe-Barret flies over the enemies and blasts them, dealing huge damage.  For some reason, I couldn't get this one, even though I saved North Corel.  After the North Corel train incident, talk to the lady in the tent to receive this.

Victory Dance
Barret loads and reloads his gun repeatedly.