Roberto Mario Castro (born June 23, 1985) is an American professional golfer who plays on the PGA Tour.

In 2005, Castro was the captain of the United States Palmer Cup team that defeated Europe 14–10.

Castro played on the eGolf Professional Tour from 2007 to 2010 and won five events during that time.

He played in 12 events on the Nationwide Tour in 2010 and recorded a runner-up finish at the Preferred Health Systems Wichita Open.

On May 9, 2013, Castro shot a 63 on the opening day of The Players Championship to equal the course record set by Fred Couples (1992) and Greg Norman (1994).