The eldest of the three Autobot Brothers. X-Brawn loves extremes and can handle any type of environment, from desert to blizzard, and can traverse some of the toughest terrain. He lives for the thrill, and can often be found climbing the tallest towers in the city in car mode, using his winch to pull himself up the buildings. He is a martial arts master, and has enormous strength in his left arm, which he uses to execute lariats (a pro-wrestling maneuverer) on his Predacon opposition. X-Brawn is a bot of few words, but is very reliable.

When Optimus Prime's brother, Ultra Magnus, came to Earth and forced Prime into a combination that allowed him to share the power of the Matrix, Magnus's link to the Matrix resulted in him inadvertently channeling its energy in the midst of a battle. That energy involved Prowl, Side Burn and X-Brawn, "supercharging" them into newly-colored, more powerful bodies. After a brief amount of training, Prowl and the others were soon able to control this new ability, shifting to "Supercharge Mode" when an extra power boost was needed in battle. Their supercharged modes afforded them no advantage in their final battle with Galvatron, however, as they were strung up and had their energy drained by the villain, until Optimus Prime and Ultra Magnus challenged him to a final battle at the Earth's core, and defeated the villain.

(From Wikipedia)