King Condor makes his final foray against the Blackhawks in a Dillin and Cuidera story in Blackhawk 209 (June 1965).
The Blackhawks engage in some really lame physical comedy stuff before King Condor shows up. The villain now has a bird body, which he shows off to his old foes before he begins robbing airplanes. He is not merely bragging, his plan involves having the Blackhawks follow him.
Blackhawk and Hendricksen trail King Condor to an island of bird men. These guys are being forced to work for King Condor, and explain how they were shipwrecked on the island long ago. The water causes them to develop bird bodies, but some herbs on the island prevent the change. King Condor came and stole all the herbs, and now forces them to rob for him. He also knocks out the two Blackhawks, and makes them drink the water, giving them bird bodies when they wake up.
King Condor makes Blackhawk and Hendricksen rob for him, though Blackhawk notifies the locations ahead of time, making sure they rob things of no value. It's all a delaying tactic until the team can get the upper hand with King Condor, and get the herbs back. Then they give everyone human bodies again.
It's probably a good thing King Condor never made another appearance.