William Albert Nimick (September 2, 1848 – January 19, 1907) was a part owner of the Pittsburgh professional baseball team in Major League Baseball, and was president of the team during the 1885–1890 seasons. Initially nicknamed the Alleghenys, the franchise has been known as the Pittsburgh Pirates since 1891. The team competed in the American Association from 1882 through 1886, and has been a member of the National League since 1887. A native of Pittsburgh, Nimick died in Pasadena, California, in 1907.