9. Michelle Thomas; Myra Monkhouse
Like Steve Urkel, the character of Myra Monkhouse was originally a one time character who appeared in season six. Then she and Steve developed a romance and she stuck around as a regular character. Michelle Thomas was the actress who played Monkhouse. For three seasons producers cultivated their romance. By season nine they’d broken up. Similar to the disappearance of Judy Winslow, when the romance of Michelle and Steve left the show, so went the character of Monkhouse. Without much explanation, she faded into nothingness.