William Louis Hassamaer
- Bats Unknown, Throws Unknown
- Height 6' 0", Weight 180 lb.
- Debut April 19, 1894
- Final Game July 6, 1896
- Born July 26, 1864 in St. Louis, MO USA
- Died May 29, 1910 in St. Louis, MO USA
"In the voting contest for the most popular Senator, Roaring Bill Hassamaer leads . . ." - Sporting Life, July 6, 1895
Roaring Bill Hassamaer played three seasons in the majors. He was a regular on the 1894 Washington Senators, playing right field as well as infield and posting the second highest batting average on the team.
He was a regular again in 1895 but his batting average slipped and he was sold to the Louisville Colonels near the end of the season. The following season with the Colonels, he continued to hit for a low average and he appeared in his last major league game on July 6.
He continued to play in the minors through at least 1899.