J.J.K (Janus) Ooms (15 Augustus 1866, Amsterdam – 6 November 1924, Amsterdam) was a Dutch rower who was the first non-Briton to win the Diamond Challenge Sculls at Henley Royal Regatta (in 1892). Ooms rowed for Neptune Rowing Club, Amsterdam, and was trained by who also trained the Olympic champions François Brandt and Roelof Klein. In 1886, a group of interested sportsmen established a regatta in Amsterdam after meeting at the café Suisse "to establish the “Committee for the Championships of the Netherlands for gentlemen amateurs in single scull outriggers".