Seven. According to Optimus Prime, it is known that Optimus Prime has changed seven owners. The ox king "Optimus Prime" is a yellow ox, which has won numerous awards and had seven owners. The story of Optimus Prime is wonderful. When he was a cowboy, a cattle dealer in Lvliang Xincun took him from Baoshan to Lvliang. After seven changes of hands, he was called Optimus Prime.