Mercy Chapel at Mill Run is an historic Carpenter Gothic-style church located at Selbysport, Garrett County, Maryland. It is a one story, one room frame structure built on an octagonal plan above a coursed stone foundation. The interior of the chapel is a fine example of local craftsmanship and is virtually unchanged since the 1870s. Two small graveyard plots lie adjacent to the chapel. It is one of the most architecturally sophisticated and well preserved octagonal buildings in Maryland, and one of only a dozen mid-19th century octagonal buildings surviving in Maryland.