Portrayed by 18-year-old Josh Weinstein* (today known as J. Elvis Weinstein), Dr. Laurence Erhardt was the original sidekick to Dr. Clayton Forrester on TV's Mystery Science Theater 3000. With his glasses and curly hair he gadded about a control room in the Gizmonics Institute in the KTMA season of the show and then moved to Deep 13 for Season 1 when the show went national. While the later character of TV's Frank was clearly a subordinate to Dr. Forrester, Dr. Erhardt was a colleague and the working relationship between the two was much friendlier than that of Dr. F and TV's Frank. The name "Laurence Erhardt" was chosen by Weinstein because it sounded pretentious, something that the character was in spades.
At the end of the first national season of MST3K Weinstein left the series to pursue a career in Hollywood (some speculate that he was about to be fired for failure to stick to the scripts during the movie in his role as Tom Servo). To maintain series continuity Dr. Erhardt was declared "missing" in Episode #201 when TV's Frank stepped into the series. Afterwards, he was mentioned only once more in the history of the show. During the Episode #313, Earth vs. The Spider, a character in the film vaguely resembled the missing doctor, and when he was eaten by the spider Joel called out "Dr. Erhardt, no! So that's what happened to him!"
Seeing as how Season 1 episodes of Mystery Science Theater 3000 are so scarce today, the best chance to see Dr. Erhardt in action is on the Rhino Home Video release of episode #106: The Crawling Hand.
* This is not the same Josh Weinstein as seen in the credits of The Simpsons.