Wladimir Klitschko is a Ukrainian former professional boxer who competed from 1996 to 2017. He held multiple heavyweight world championships between 2000 and 2015, including unified titles between 2008 and 2015. During this time he also held the International Boxing Organization (IBO) and Ring magazine titles. Klitschko is considered by some to be one of the greatest heavyweight champions ever. He was known for his exceptional knockout power, using a strong jab; straight right hand; and left hook, quick hand speed, formidable physical strength, and his athletic footwork and mobility – unusual for boxers of his size. World heavyweight champion (IBF) from April 22, 2006 to February 23, 2008. Wiki link