Wladimir Klitschko has a degree from Kiev University.
Also, Audley Harrison has a BSc (hon) in sports & leisure from Brunel University and of course an olympic gold medal, but I bet his WBF 'world' heavyweight title dosen't count
I was thinking of Bonecrusher Smith, but he was just a college grad and won the WBA title...dun know anything about him being an amateur though, so I that scraps him out.
Yes, Bonecrusher Smith and Vitali Klitschko both have degrees and have won a version of a world title, but they didn't win an olympic gold medal.
Muhammad Ali may have picked up an honourary degree from some university along the line - would that count?