I just remembered Darth Nihilus from KOTOR.
GW changed Malekith's name to Malerion to Warhammer Fantasy. Probably the biggest motivator was the worry of a lawsuit by the Mouse.

So how long until GW changes the Warhammer 40k Dark Imperium's high gothic name being Imperium Nihilus to something else out of fear of Mouse throwing an army of lawyers at GW?