The Fire Count is a villain who appears in "His Hero." He wears a crown which suggests that he may have been the previous ruler of the Fire Kingdom, despite his title as "count." He is made out of fire and has no other physical aspects aside from his face. He can be considered a "representation" of Ice King, in the sense that Billy is Ooo's old equivalent of Finn. Considering that he is a count, it can be speculated that he is related to Flame King and Flame Princess in some way. In his appearance, Billy fought him and rescued the Cotton Candy Princess.
His face slightly resembles Ice King's in that he has a goblin-like nose and sharp teeth. His crown also has tall points like Ice King's. Otherwise, he looks like a classic fireball, except inverted so that the rounded part of the flame is towards the top and the tip of the flame is at the bottom.
The Fire Count was originally named the Fire King. The change was made very late in the production of "His Hero"