Byrnside-Beirne-Johnson House, also known as "Willowbrook," is a historic home located near Union, Monroe County, West Virginia. The house began as a pioneer log fort built by six families in 1770. After 1855, it was enlarged to a large 2½-story, five-bay, "T"-shaped dwelling with a two-story rear wing. It is covered with board-and-batten siding in the Gothic Revival style. The front features a two-story gable end porch built about 1900. Also on the property is a contributing smokehouse. It was listed on the National Register of Historic Places in 1991.