Of course he was always on, but at one point was a television actor.
Taking on a a role that was not far from his own personality, he played a crazily seductive scientist and demonstrator who was tempting people to sniff ether.
The show was an early Nova episode called "Strange Sleep" about anaesthesia. It aired for the first time on PBS on April 4, 1974, and in 1975 won the Red Ribbon at the American Film Festival.
Unfortunately, there are no links to view the episode over the Web, but I will keep looking and post a link here if I find one or if I find a place to buy it from.