Cornelius Eugene Urkel aka OGD, portrayed by Jaleel White, is Steve and Myrtle Mae Urkel's cousin from Detroit. In his first appearance of season 9's Original Gangsta Dawg, it was revealed in an early scene that Steve refuses to give him money even though he was in serious trouble with a tough, tall thug named Fresh Squeeze (played by Mongo Brownlee) and tries to avoid him. Before leaving to be with their uncle on a nuclear-powered submarine vessel, Steve warns him not to return to the Winslow home while he's gone. Cornelius having ignored Steve's warning, returns anyway and impresses Eddie and 3J, but his behavior disgusts Carl, Harriette and Laura. He gives the boy a CD that contains rap lyrics that clearly disrespect police officers, which enrages Carl because he's a proud officer of the law. Sometime later, Harriette learns from the grandmother whom Cornelius lives with that he's a good kid but his hate for the police both had something to to with the people he hangs out with and where he's from. She tells Carl he can change his opinion about the police by giving him a positive outlook on them. He's worried that Cornelius will be a bad influence on 3J and Richie. Harriette tells him that they can only hope they rub off on him first beforehand. Later on at the house, Carl was confronted by Fresh Squeeze and tricks the thug in letting him accompany him to where OGD is.
At the Sizzle Club after Missy Elliot's performance, he was seen trying to hit on Laura and makes a nasty comment to Stefan causing him to call Steve in the nuclear submarine's control room. During a conference call between Steve, Stefan and Cornelius, Steve warns him to return to Detroit at once, and Stefan warns him that he could go in a box or a bus; it's his decision. Cornelius makes a comment that's tough talk from a man in Milan. Steve corrects him that he's gonna be back tomorrow to deal with him.
At the house, Cornelius has learned from Carl that Fresh Squeeze has been at the Winslow home and he attempts to run. He in turn tells him that the thug won't bother him again because he's locked up in his own cell. Carl admitted to Cornelius that he recognized Fresh Squeeze because he used to run illegal operations in Chicago and left for Detroit when they put out a bulletin for his arrest. He also tells him that he was accompanying him and made a detour to the precinct he works at. Carl wished Cornelius saw the look on the thug's face when five officers surrounded his car and said "Surprise!" He apologizes for his comments about police officers and tells Carl he'll leave in the morning. He convinces him to stay for a while longer. The next day, Cornelius offers 3J advice in a positive light by telling him he's got a loving family and a steady home to come to. Steve comes in to confront him after learning from Stefan he was hitting on Laura while he was away. Cornelius apologizes and leaves while Urkel embarrasses himself with peace lines.
If the show had gone on for its final season, it would've been revealed that Cornelius would've been mentored by Carl and that he overcomes the negative influence of his former friends. Stefan and him traded places for one day and found themselves in a better understanding with each other. Cornelius finds love in Myra and both take their relationship slowly. She accompanies him in a tour across America to encourage teens in similar situations that he was in that they can make it in this world. Upon returning, he would help Eddie rescue Carl from a dangerous thug seeking revenge against him for being locked up a long time ago. Before leaving to help reform his home in Detroit, Cornelius and Myra witness the birth of Steve and Laura's daughter, Stephanie Laurine Urkel.
- The name Cornelius was originally used in the episode Father of the Bride as the middle name of one of the "Urkel kids" in Carl's nightmare. This character is the oldest of the three sons in the group, sounding rather laid-back and cool (like his mother Laura), but is still nerdy enough to take after his father Steve. If this character was Steve's real son, despite disliking his cousin, Steve probably would give his son this middle name to honor him.
- Cornelius is the 2nd character from Detroit to appear on Family Matters, the first being Clarence.