Brett Nelson (born 1969) is an American multi-instrumentalist, singer and songwriter best known as the former bassist for the indie rock band Built to Spill.In high school, Nelson played in a band called Farm Days along with Doug Martsch and Andy Capps. Nelson's next band, Butterfly Train, released two albums on Up Records, in 1994 and 1996, before breaking up (Andy Capps was drummer for the latter album).In 1994, Nelson and Andy Capps joined Martsch's Built to Spill.