Brad Martin Hennessey (born February 7, 1980 in Toledo, Ohio) is a Major League Baseball pitcher in the Baltimore Orioles organization. He throws and bats right-handed. He attended Whitmer High School where he was coached by Gary O'Connor.
Hennessey was drafted by the Giants in the first round (21st overall) of the 2001 Major League Baseball Draft out of Youngstown State University.
After posting a 2.38 ERA in nine Northwest League starts, he was diagnosed with a cancerous tumor in his back. He had it removed in February 2002, but it grew back later that season, putting him out for the rest of the season.