José Manuel Guillén (pronounced [ɡiˈʎen]; born May 17, 1976) is a Dominican former professional baseball outfielder.

On July 23, 1999, Guillén was traded, along with Jeff Sparks, to the Tampa Bay Devil Rays for Joe Oliver and Humberto Cota.

On July 30, 2003, Guillén was traded by the Reds to the Oakland Athletics for Aaron Harang, Joe Valentine, Kyle Wallace, and Jeff Bruksch.

In 2004, he hit .294 with 27 home runs and 104 RBIs for the Angels, but he was suspended the last two weeks of the regular season and during the postseason for "inappropriate conduct" in publicly expressing his displeasure with Angels manager Mike Scioscia following Scioscia's removal of Guillén in favor of a pinch runner during a crucial game against the Oakland Athletics.

Going into the series, both Guillén and Scioscia kept a civil tone publicly, each indicating that the past was behind them and claiming that they held no hard feelings toward each other.

However, the tensions below the surface were exposed when, during the second game of the series, Angels pitcher Brendan Donnelly was found with illegal substances on his glove.

As he was being restrained by fellow Nationals players, Guillén shouted angry words at the Angels, a number of whom made it clear that they felt their former teammate had been the one who told Robinson to have Donnelly's glove examined.

After the series' final game, Guillén blasted Scioscia and acknowledged that despite his earlier statements to the contrary, he was in fact still hurt over what had happened at the end of the 2004 season.

Martinez hit him with a pitch twice, and after the second time Guillén charged the mound, only to be held back by Paul Lo Duca and umpire Ted Barrett.

In a game on August 26, 2008, in Kansas City against the Texas Rangers, Guillén was involved in a confrontation with a fan in the stands just past the Royals dugout down the first base line.

[9] On August 13, 2010, Guillén was traded to the San Francisco Giants for cash and a player to be named later[9] which turned out to be Kevin Pucetas.

In 2009, he acknowledged that he had worked "for many years" with Angel Presinal, a personal trainer closely linked to performance-enhancing drugs and who is currently banned from major league clubhouses.

[12] In 2010, MLB began an inquiry on shipments of human growth hormone received by Guillén, and directed the Giants to keep him off their postseason roster.

[11] On November 14, it was revealed that the DEA had intercepted a package of fifty HGH syringes en route to Guillén's house.