Howard the Duck and Mork

I still remember Robin Williams' first appearance as Mork on a episode of Happy Days.  It made a big impression and I distinctly recall the kids at school discussing it at school the next morning.  I was at the right age to really get a kick out of his antics, so I thought that it was cool to see him cast as Popeye a few years later.  He and Shelley DuVall really embodied their roles in that one, still two of my favorite comic book character performances ever.