Heidi Blair Pratt (born Heidi Blair Montag; September 15, 1986) is an American reality television personality. She is known for starring on the former MTV reality series The Hills. At one point, the series, which aired from May 2006 through July 2010, followed the life of her former friend and housemate, Lauren Conrad, then later followed Kristin Cavallari, another friend of Montag's.