Gaylord Picaro was born in Reading, Pennsylvania. When we first see Pit Bull he's in the Pitt's surrounding area with his band of scavengers, the Wardogs. While there, he found half of the paranormal group DP7. He fought their leader Jennifer Swenson,she threw a grenade at him, buying time for the team to retreat. He decided to followed Meriam Sorenson and encountered her team mate Dave Landers. During their fight Pit Bull bit Dave, angered Dave broke Pit Bull's jaw and slammed him into a wall.
Not long after, the US started drafting all the paranormals into the army. At Fort Benning, he began to relentlessly pick on Harley Mook. This led to Mook's attempt to kill Pit Bull. Jeff Walters managed to save his life and Pit Bull has considered Jeff his best friend ever since.
Durind his time at Fort Benning, the paranormal team Psi-Force attacked, trying to free their teammate Thomas Boyd. Pit Bull tried to stop Boyd, but was overpowered by him.
Later, Psi-Force's Tyrone Jessup was captured and brought to Fort Benning. Not learning his lesson, Pit Bull began picking on Tyrone. Jessup got his revenge by injuring Pit Bull during a training exercise.
Gearing up for World War 3, Pit Bull met the Paranormal Platoon's commanding officer, Major Kathi Blizzard. The platoon was given a pass, and Pit Bull tried to go AWOL. Pit Bull soon encountered Sgt. Haldeman, and was sent back. The next day the platoon went to South Africa.
Soon after arriving Pit Bull noticed something was wrong when he noticed the hatred Colonel Oort possessed toward Jeff Walters, based purely on Jeff's skin color. The platoon were ordered by Colonel Oort to attack the rebels that he claimed were sheltering the paranormal responsible for destroying Pittsburgh. During the battle Pit Bull was left behind when the platoon was ordered to pull out. Pit Bull went berserk, and massacred the rebels before he was reunited with the rest of the platoon.
The platoon then destroyed Colonel Oort's tanks, rescued Blizzard and Walters, and they all fled back to America.
Years later, Nightmask assembled a group of paranormals, including Pit Bull, to stop the alien invasion of Skeletron. Kayla Ballantine, now possessing the Starbrand, appeared before the group warning them that Skeletron was close. Quasar soon arrived and took the group to Skeletron's ship. Skeletron was eventually defeated and trapped in the New Universe, and the Stranger brought the New Universe Earth to the regular Marvel Universe to study it. Their Earth was then sealed off by the Living Tribunal.