Throughout the years there have been a few celebrity VAs that portrayed guest characters in some of the sequels, here's a list of the ones I could find:
Nancy Cartwright (Dana, in LBT VI)
Kris Kristofferson (Doc, in LBT VI)
Michael York (Pterano, LBT VII)
Robert Guillaume (Mr. Thicknose, LBT VIII)
Kiefer Sutherland (Bron, LBT X)
James Garner (Pat, LBT X)
Bernadette Peters (Sue, LBT X)
Camryn Manheim (Tria, LBT XI)
Michael Clarke Duncan (Big Daddy, LBT XI)
Sandra Oh (Doofah, LBT XIII)
Cuba Gooding Jr. (Loofah, LBT XIII)
Reba McEntire (Etta, LBT XIV)
Damon Wayans Junior (Wildarms, LBT XIV)
Which one is your favourite? Which ones did I miss?
Thanks to somerandomfangirl for pointing out that Nancy Cartwright (the voice of Bart Simpson) was Dana's VA.