Use of the contrabass trombone goes back to the Renaissance and predates the tuba.  It may be pitched in BBb, CC, or F.  Most models have one or two valves to extend the low range further and to increase agility on such a large instrument.  Contrabass trombones may be found in trombone choirs, some symphonic and opera music, and in large orchestras used for movie soundtracks.  Mouthpieces are sized in between bass trombone and tuba sizes.