Joseph William Kelly Jr. (born June 9, 1988) is an American professional baseball pitcher who is a free agent.

Kelly has gained publicity for his comical repertoire, such as dancing in the outfield during practice, disguising himself while interviewing the unwitting rapper Nelly, engaging in a lengthy staredown with Los Angeles Dodgers outfielder Scott Van Slyke before a 2013 National League Championship Series game, and wearing a charro jacket to the White House.

After high school, he attended the University of California, Riverside (UCR), and played college baseball for the Highlanders team.

[9] Kelly made his professional baseball debut with the Batavia Muckdogs of the Class A Short Season New York–Penn League, where he appeared in 16 games (two starts), posting a 4.75 ERA with 30 strikeouts in 30+1⁄3 innings pitched.

[10] In 2010, the Cardinals mainly used Kelly as a starting pitcher with the Class A Quad Cities River Bandits to get him more innings and develop his secondary pitches.

[11] For the season, Kelly appeared in 26 games (18 starts) and pitched 103+1⁄3 innings while registering 92 strikeouts and 45 walks with a 4.62 ERA and 6–8 record.

[10] Kelly made his MLB debut on June 10, 2012[12] replacing the injured Jaime García in the Cardinals' starting rotation.

[13] Kelly pitched seven innings in his MLB debut, against the Cleveland Indians, allowing seven hits and one run while striking out four batters; he received a no decision in the game.

[19] After spring training in 2013, Kelly lost his rotation spot to rookie Shelby Miller and was relegated to the bullpen for much of the first half of the season, seeing little use.

[22] During the 2013 Cardinals regular season, Kelly had 37 appearances (15 starts), registering a 10–5 record and 2.69 ERA, with 79 strikeouts in 124 innings pitched.

[16] On October 6, Kelly made his first postseason start against the Pirates in the 2013 National League Division Series, receiving a no decision in Game 3.

[25] In Game 6, Kelly and Dodgers outfielder Scott Van Slyke created a stir before the first pitch by engaging in a lengthy staredown.

They maintained their positions with hats over their chests through the ground crew's preparation of the field and starting pitcher Michael Wacha's warmup pitches.

A total of about 15 minutes passed before the annoyed home plate umpire, Greg Gibson, motioned to both players.

[31] In ten starts for Boston, during August and September, Kelly went 4–2 with a 4.11 ERA while striking out 41 and allowing 32 walks in 61+1⁄3 innings.

[16] In January 2015, Kelly made a guarantee to the Boston media that he would win the AL Cy Young Award the following season.

[39] By the end of the 2016 season, after spending time with the Triple-A Pawtucket Red Sox, Kelly's role with Boston was as a relief pitcher.

[40] During the regular season he made 54 appearances, all in relief, compiling a 2.79 ERA with 4–1 record in 58 innings pitched; he had 52 strikeouts and issued 27 walks.

[49] Kelly struggled in the early part of the season for the Dodgers and had an 8.35 ERA on June 1, causing him to be booed by the homefield fans.

[16] In Game 5 of the National League Division Series, Kelly gave up a 10th inning grand slam to Howie Kendrick, and was tagged with the loss.

[53] On March 14, 2022, Kelly signed a two-year, $17 million contract with a club option for the 2024 season with the Chicago White Sox.

[54] Kelly struggled in his first year with the White Sox, going 1–3 with a career worst 6.08 ERA in 43 games in 37 innings while striking out 53 batters.

[16] On July 28, 2023, Kelly and Lance Lynn were traded to the Dodgers in exchange for Trayce Thompson, Nick Nastrini, and Jordan Leasure.

Kelly shared a condominium for a time with Shelby Miller, with whom he competed for a rotation spot during spring training 2013.

[68] Kelly received a charro jacket in a jersey swap with a mariachi musician in celebration of his Mexican heritage and wore it to the Dodgers' championship trip to the White House following the 2020 season.