Dr. Venom was unknown in the cartoon and didn't have a figure for many years, but he was the source of many plots in the early Marvel comics run. He's probably most known for his Brainwave Scanner, which would be used time and again in the comics, and also for his rivalry with Kwinn and Snake Eyes. Considering all his plots, the M.O. "evil scientist" seems appropriate.
Dr. Venom is a simple design. All you need is a guy in a long coat. I used a Doc Ock Heroclix, removing his robo-arms and filling the holes with green stuff.