Keith Charles Foulke (/foʊk/ FOHK; born October 19, 1972) is an American former Major League Baseball relief pitcher. A graduate of Hargrave High School in Huffman, Texas, Foulke attended Galveston College and Lewis–Clark State College. Between 1997 and 2008, he pitched for the San Francisco Giants, Chicago White Sox, Oakland Athletics, Boston Red Sox and Cleveland Indians. Foulke was an All-Star in 2003 and he earned the save in the final game of the 2004 World Series.

After graduating from Hargrave High School in Huffman, Texas, in 1991, he attended Galveston College and Lewis–Clark State College in Idaho. He began his career in the minor-league system of the San Francisco Giants. During the 1997 season, Foulke was one of six prospects (along with Bob Howry, Lorenzo Barceló, Mike Caruso, Ken Vining, and Brian Manning) traded to the White Sox in exchange for Wilson Álvarez, Danny Darwin, and Roberto Hernández in what became known as the White Flag Trade.

In 1998, Foulke found a home in the White Sox bullpen, primarily serving as set-up man for closers Matt Karchner (who was traded to the Chicago Cubs in the middle of the season) and Bill Simas. In 1999, Foulke established himself as one of the league's best relief pitchers, posting a 2.22 ERA in 105.1 innings of work over 67 games, however, he was still used primarily as a set-up man. His stellar season even netted him a vote for the 1999 AL Cy Young Award.

In 2000, Foulke again was an important piece of the White Sox bullpen. Though Bob Howry entered the season as the team's primary closer, Foulke was seeing more and more time closing out games, and by April's end he had recorded 4 saves (in 1999, he didn't notch a save until June). As Howry continued to struggle, Foulke inherited the closer's role and flourished, saving 34 games for the White Sox in 2000, and was a major reason the White Sox won the AL Central title.

On December 3, 2002, Foulke, along with catcher Mark Johnson, minor league pitcher Joe Valentine, and cash, was traded by the White Sox to the Oakland Athletics for closer Billy Koch and two minor leaguers. During the 2003 season with the Athletics, Foulke would distinguish himself as a closer, leading the league in saves and games finished, being named to the All-Star team and winning the American League Rolaids Relief Man of the Year Award. However, it was Foulke who also gave up the game-winning double to David Ortiz in Game 4 of the American League Division Series that year.

Foulke was granted free agency on October 27, 2003, and signed with the Boston Red Sox.

Foulke continued his dominance in his first year with the Red Sox, saving 32 games in 39 opportunities while racking up 79 strikeouts and a 2.17 ERA across 83 innings. In the 2004 postseason, Foulke appeared in 11 of 14 games, throwing 257 pitches over 14 innings. He would rack up 19 strikeouts and over the entire stretch would only allow exactly one earned run. While Foulke was marvelous (1.80 ERA) in the World Series, his most crucial work was in the American League Championship Series against the Yankees, when he pitched in five games and didn't allow a run. With the Red Sox down, 3–0, in the series, Foulke threw 100 pitches over the next three days to help his team force Game 7. Foulke was on the mound when the final out was made in the 2004 World Series. He induced Édgar Rentería (who would be his teammate the next season) of the St. Louis Cardinals to hit a one-bounce ground ball back to him which he flipped to first, thus clinching the Red Sox' first World Series Championship since 1918, ending the Curse of the Bambino. Fox commentator Joe Buck famously called the grounder with:

Back to Foulke. Red Sox fans have longed to hear it: The Boston Red Sox are World Champions!