The banjo was probably first used mainly as a rhythm instrument, in klezmer bands in the USA in the first half of the 20th century.
Klezmer banjo players in the late 19th and earlier 20th centuries included:
USA Berish Katz (also violin)
Klezmer banjo players in the later 20th century and today include:
Russia Roman Shinder (also guitar)
USA Avi Fox-Rosen (also guitar), Henry Sapoznik, Pete Rushefsky (also guitar, tsimbl)