L. Joan MacAlpine-Stiles (known earlier in her career as Joan MacAlpine) is a politician in the province of New Brunswick, Canada. She served as Member of the Legislative Assembly (MLA) for Moncton West from 1999 until 2010. She is the wife of fellow MLA Wally Stiles; they were married while in office in 2005.

She previously served in the province's cabinet from 1999 to 2006.

MacAlpine was elected to the Moncton City Council in 1992, 1995 and 1998 before resigning to accept her seat in the legislature.

On April 17, 2007, she announced that she would cross the floor to join the Liberal party, along with her husband and fellow MLA Wally Stiles.^[1] She did not stand for reelection in 2010.^[2]