The Ever-Mysterious Horde Prime in She-Ra
The fact is in She-Ra, I believe there was this much added character known as Horde Prime whose name is first mentioned when his son Prince Zed is introduced. The fact that Prince Zed is Hordak's nephew suggests that he could be Hordak's brother or brother-in-law, but which is which is not known. Seeing however that plenty of the Horde's ships bear a Hordak face may suggest they are both brothers and look alike.
However nobody has ever seen Horde Prime's real visage (except for a metallic hand that came out) so I assume he must have transformed into that form but it was never explained. Later it is alluded that he actually has not one but TWO heads when Grizzlor suggested to Hordak to give a pair of matching bowties, one for each head and Hordak says that his brother has two of everything. However in non-canon comics, Horde Prime is shown to have only one head and not a hidden in smoke monster.