St. Mark's Episcopal Church is an historic Episcopal church located at 6-8 Highland Street in Ashland, New Hampshire, in the United States. It is part of the Episcopal Diocese of New Hampshire. The single story Gothic Revival frame building was designed by New York City architect J. Coleman Hart, and built in 1859 for a congregation established in 1854; a parish house was added south of the main building in 1898-99. The exterior of the building consists of half-timber framing filled with brick usually laid in stretcher bond, and set on a granite foundation. Stained glass windows are set in their own panel sections, and have cinquefoil arched heads and beveled surrounds. To the southeast of the main block stands a tower with an open belfry, which is topped by a hip roof that transitions into an octagonal steeple shingled with fishscale wood shingles.