Donald Roland "D.J." Trahan, Jr. (born December 18, 1980) is an American professional golfer.

Trahan was born in Atlanta, Georgia. He moved to Hilton Head Island, South Carolina, where he attended Hilton Head Island High School. He then moved to Spartanburg, South Carolina where he attended and graduated from Paul M. Dorman High School. He attended Clemson University. He won the U.S. Amateur Public Links in 2000 and represented the United States in the 2001 Walker Cup and the 2002 Eisenhower Trophy.

After turning professional in 2003, Trahan spent 2004 on the Nationwide Tour winning the final full-field event of that season at the Miccosukee Championship. He was a PGA Tour rookie in 2005 and won his first PGA Tour title at the 2006 Southern Farm Bureau Classic which was an alternate event to the WGC-American Express Championship. He won his second event at the Bob Hope Chrysler Classic by three strokes over Justin Leonard on January 20, 2008. He has featured in the top 100 of the Official World Golf Rankings.