Former mixed martial arts fighter and UFC champion B.J. Penn was arrested in Hawaii on assault charges this past weekend.

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The 36-year-old fighter was reportedly involved in a parking lot altercation that saw him beat a man so badly that the victim was hospitalized with a broken eye socket.

According to TMZ Sports, Penn had been partying pretty hard in Maui when he started getting aggressive with his fellow boozers. One person -- reported to actually be a friend of Penn's -- stepped in, and was gifted with a trip to the emergency room for his troubles.

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Penn left the scene but was later arrested at his hotel room by local authorities. His charges are said to be for assault in the second degree.

Long regarded as one of the best pound-for-pound fighters in UFC history, Penn dominated the lightweight division with a undefeated record for eight years, before moving up to compete in the welterweight class as well. This is not a first run in with the law for Penn. Uproxx has a full list of his prior violent episodes.

Watch highlights of BJ Penn's career below: