Jean-Baptiste Frédéric Isidor, Baron Thielemans (born 29 April 1922, Brussels, Belgium), known as Toots Thielemans, is a Belgian jazz musician well known for his guitar and harmonica playing as well as his whistling. Thielemans is credited as one of the greatest harmonica players of the 20th century. In 2009 he became NEA Jazz Master, the highest honour for a jazz musician in the United States.