Since she’s gone solo she alternates between Bass and Guitar. Each time I’ve seen her live she’s played Bass on about half the songs. On the albums it’s about the same. But she was definitely the Bass Player while she fronted Til Tuesay.
Greg Lake - Emerson, Lake and Palmer
A whole slew for King Crimson: Greg Lake again, Boz Burrell (horrible), John Wetton and a couple of other less important ones.
Most of the best ones have been listed already, but there’s still…
Glenn Hughes (later version of Deep Purple, among other bands)
Tony Lewis (the Outfield)
Randy Meisner & Timothy B. Schmit (Eagles)
Benjamin Orr (the Cars)
Brian Wilson (Beach Boys)
Kip Winger (Winger)
I know that Brian WIlson played other instruments besides bass, and I know Meisner & Schmit shared vocal duties with several other guys… but I think they still count.
That’s all I’ve got where the lead singer is the bass player, but if you’re counting bands whose bass player sings lead on some of the songs:
John Lodge of The Moody Blues
Colin Moulding of XTC
Ben Orr of The Cars
Michael Steele of The Bangles (oops—I see astorian beat me to it)
John Munson of Trip Shakespeare and Semisonic