Grant Robert Balfour (born December 30, 1977 in Sydney, New South Wales, Australia) is a relief pitcher for the Tampa Bay Rays. He has previously played for the Minnesota Twins and Milwaukee Brewers. Balfour is well known in some baseball circles for his seemingly ironic name (Ball-Four), considering the fact that he is a pitcher.

Balfour spent his high school years at William Clarke College in Kellyville, Sydney, Australia.

Balfour made his major league debut with the Minnesota Twins in 2001 and played with them until 2004. After missing 2005 with an injury, in 2006 he played in the Cincinnati Reds organization. After a three-year absence, Balfour made his return to the major leagues on July 18, 2007, in the 8th inning with the Milwaukee Brewers. He relieved Chris Capuano in a 2-2 tie with the Arizona Diamondbacks, striking out Chris Young, the first hitter he faced. With two outs in the 8th, he hit a batter and walked another before giving up a three-run home run to Mark Reynolds, giving the Diamondbacks a 5-2 lead. Balfour would finish the 8th and 9th inning and take the loss in relief, having given up three earned runs in the 5-2 defeat.