William "Cannonball" Jackman (October 7, 1897 – September 9, 1972) was an American professional baseball pitcher in the Negro leagues. He played from 1925 to 1942 with several teams, including a spot on the otherwise all-white East Douglas team in Massachusetts's amateur Blackstone Valley League in 1929, a squad which also featured 18-year-old newcomer Hank Greenberg.
Jackman received votes listing him on the 1952 Pittsburgh Courier player-voted poll of the Negro leagues' best players ever."1952 Pittsburgh Courier Poll of Greatest Black Players"
References
External links and Baseball-Reference Black Baseball stats and Seamheads Negro League Baseball Players Association Bill Jackman at SABR Bio Project