Buzz Osborne (also of Fantomas, Venomous Concept) Dale Crover (also of Altamont, Porn)
plus more bassists over the years than you have had hot dinners, including Shirley Temple's daughter, original Mudhoney bassist Matt Lukin and even Gene Simmons from Kiss for one show. The most recent one is
Slide bass overlord Kevin Rutmanis (also of Tomahawk, ex-Cows)
They have been delighting/annoying audiences since 1983 and have managed to release a lot of records while constantly evolving and inspiring along the way. Many consider them to be the founding fathers of grunge and back in the day they had the world's most famous roadie in Kurdt Kobane. He probably made them hundreds of cups of coffee.
Since 1999 their home has been Mike Patton's Ipecac records for whom they have released a whopping six new albums, three reissues and a very nice art book in celebration of their twentieth anniversary.
For a good overview of their vast back catalogue try looking at Mark Prindle's excellent review page here.