Emperor penguin (Aptenodytes forsteri): King penguins and emperor penguins are sister species, meaning they share a recent common ancestor and are each other's closest relatives. The emperor penguin is slightly larger than the king penguin and known for its remarkable breeding behavior in extreme Antarctic conditions.
Northern rockhopper penguin (Eudyptes moseleyi): While not as closely related as emperor penguins, the northern rockhopper penguin belongs to the same family (Spheniscidae) as king penguins. Rockhopper penguins have distinctive yellow head plumes and are known for their energetic movements while on land.
Other closely related penguin species include:
Macaroni penguin (Eudyptes chrysolophus): Macaroni penguins have distinctive golden crests and are found at subantarctic islands.
Royal penguin (Eudyptes schlegeli): Royal penguins exhibit striking yellow crests and inhabit Macquarie Island and nearby subantarctic regions.
Snares penguin (Eudyptes robustus): Found breeding mainly at the Snares Islands, these penguins have bright yellow crests as well.
While these species might not be direct descendants or ascendants of king penguins, they share evolutionary relationships within the Spheniscidae family and, more broadly, the Sphenisciformes order.