Donald Mark Trahan, known as Don Trahan (born January 9, 1950), is a Republican former member of the Louisiana House of Representatives for Lafayette and Vermilion parishes.
He served a full legislative term from 2004 to 2008 during the administration of Democratic Governor Kathleen Blanco, also of Lafayette.
He served less than a year of his second term, having resigned in 2008, when he was succeeded by another Republican and his former opponent, Nancy Landry of Lafayette, who still holds the seat.