Great improvising bassist, ex-husband of Annette Peacock. Played in the seminal (and utterly dissimilar) trios of Paul Bley, Bill Evans, and Albert Ayler in the early-to-mid 60's. Subbed for Ron Carter in Miles Davis' quintet. Has appeared on many great ECM releases, as leader and sideman. Works in Keith Jarrett's trio nowadays, as well as with Marilyn Crispell, IIRC.