5. Alexander Povetkin
The talented Russian is currently linked with WBC champion Deontay Wilder, having worked his way into mandatory challenger status, however he is regarded as one of the top heavies in the world and would be a dangerous test for Fury.
Although he was outclassed by Klitschko in 2013, Povetkin has wrecked some top opposition since. However, he is not well-known outside of boxing circles and so may not have the worldwide appeal that Fury craves.