Outside of QL and BSG I know of only a few other roles, a henchman cum fall-guy in Beverley Hills Cop II, a very brief bit in the The Player, a supporting role in '84 Dune and a handful of guest appearances in the odd show here and there (SG1, Enterprise, etc).
To sum-up the man's body of work in 52 words is an insult to the wealth of entertainment he has given us, the viewing public, these last 65 years (started when he was 9yo).
While the earlier works, pre-1980's, are what clearly made him a viable property, it wasn't till the mid 80's onwards that I first found out just how great Dean Stockwell really was.
First you've got Dune, as the tormented Dr Yueh.
Next, Married To The Mob, as mob boss Tony 'Tiger' Russo. Two very different roles, worlds apart but equally enjoyable.
After that, Quantum Leap. A genuinely brilliant piece with touching moments of friendship, rye comedy, pitch-perfect drama, and a dash or two of tragedy. Albert 'Al' Calavicci, a role few actors could bring to life so well, and so believably.
Finally, BSG. A great TV Series thru and thru. Then came the end of season 2 and DEAN STOCKWELL turns up (two of him infact). Brother Cavil (John) is awe-inspiringly good (or bad depending), a twisted hate-filled monster and resentful elder-child of Ellen and Saul Tigh. Dean's portrayal of Brother Cavil is masterful. He's complex, hates his creator(s) but wants them to love him like they used to, The Lucifier Complex. He's manipulative, confident, controlled, focused but vulnerable and needy like a child.
And all without so much as a hint of QL's AL. Here's hoping there's more to come, bring on the STOCKWELL.