Did a quick Google of "bassists who play Thunderbirds," and there's actually
Link Removed (I'll copy the gist of it below)...
1. John Entwistle (The Who)
2. Gene Simmons (KISS)
3. Tom Hamilton (Aerosmith)
4. Tom Petersson (Cheap Trick)
5. Jared Followill (Kings of Leon)
6. Krist Novoselic (Nirvana)
7. Kim Gordon (Sonic Youth)
8. Mike Watt (Minutemen, The Stooges, and a slew of other bands)
9. Adam Clayton (U2)
10. Jackie Foxx (The Runaways)
Interesting they didn't mention Nikki Sixx...probably bitter about him moving to Schecter

. And I think using Krist was a bit of a stretch. When I think of Krist I think of him using aGibson Ripper (the article even mentions how the Ripper was his main bass, but he "settled on the Thunderbird in the band's final months"). I also noticed that none of the bassists/bands mentioned were particularly recent (which I would label as pre-2000, but then again I was born in 1996...so my timeframe might be a bit biased

). The most recent band/bassist mentioned was Jared from Kings of Leon...maybe the Thunderbird's usage has just been declining recently (for whatever reason).
EDIT:
A Yahoo Answers result I clicked on has a plethora of other bassists who use Thunderbirds, including Chris Squire (Yes), Shavo Odadjian (SOAD), Mikey Welsh (former Weezer bassist), Cliff Williams (AC/DC), Dean Bernardini (Chevelle)...a lot listed there.