As Duke, Ralph Brown appears in three episodes of LEXX:

Episode 3.03, Gametown
Episode 3.04, Boomtown
Episode 3.05, Gondola

Duke was a very complex fellow. Even though he was killed, it is possible he could return.
 

300 x225 pictures

A 450 x 450 picture

 
 

Special thanks to EOS Development for the wallpaper.