Jakub Šimon Jan Ryba (surname also Poisson, Peace, Ryballandini, Rybaville; 26 October 1765 – 8 April 1815) was a Czech teacher and composer of classical music. His most famous work is Czech Christmas Mass "Hey, Master!" (Česká mše vánoční "Hej mistře!"). His works mainly include many pastorellas and masses, but few compositions beyond the Czech Christmas Mass are performed regularly today. This composition is popular in many countries.