In one segment from season two, he is lost and must find a police officer to help him get home. Luckily, he encounters a police officer who turns out to be his Uncle Louie. Louie explains that it's really him under his uniform. (SSvideo)
Generally cast in sketches as a nondescript little boy, Charlie has been often performed by Frank Oz (including in the "Lost Kid" segment). Jim Henson, Jerry Nelson, and Richard Hunt have also performed him on occasion.