The Octagon House is an octagon-shaped historic house in Laurens, South Carolina. It was built in 1859 to 1862 by the Presbyterian minister and teacher, Reverend Zelotes Lee Holmes. It is notable for its architecture, as well as for being considered as the first concrete house to be ever built in the state of South Carolina.

The Octagon House is also known in various names like the Zelotes Holmes House, Old Holmes House, the Holmes-Watson House, and the Old Watson House. Most of the house?s rooms were used as domestic slave quarters, except for a small one that served as an ice house. It is designed with small hollow passages on its walls, so there could be a cooling ventilation system available.

The Octagon House was added on the National Register of Historic Places in March 1973.