Paul Allen Wood Shaffer , CM ( ; born November 28 , 1949 ) is a Canadian-American singer , actor , voice actor , author , comedian and multi-instrumentalist who served as David Letterman 's musical director , band leader and sidekick on the entire run of both Late Night with David Letterman ( 1982–1993 ) and Late Show with David Letterman ( 1993–2015 ) .
Paul Shaffer is a Canadian singer .