Jonathan O. Sánchez (born November 19, 1982 in Mayagüez, Puerto Rico) is a Puerto Rican Major League Baseball left-handed starting pitcher for the San Francisco Giants.
After being drafted by the Giants in 2004, Sánchez quickly worked his way through the Giants' farm system. In 2006, he made the major leagues and was used mostly in a long relief role. In 2007, he made the team out of spring training and was again used mostly in long relief, though he was in the minors part of the season. In 2008, he made the Giants' starting rotation, and stayed in it the entire year except for a stint on the disabled list. He started 2009 as a starter, but was moved to the bullpen during the season. He was returned to the rotation on July 10 because of an injury to fellow starter Randy Johnson, however, and he threw a no-hitter against the San Diego Padres that day. In 2010, Sánchez struck out two hundred batters for the first time and was a member of the Giants' team that won the World Series.
Sánchez throws a fastball in the low-to-mid nineties, and a curveball, change-up, and slider in the eighties.