Henry E. and Ella M. (Knott) Nicolaus House, also known as the Samuel G. and Mary Kelley House and the Rebeckah Allgood Residence, is a historic building located in Wilton, Iowa, United States.

The house was already on this property when Henry Nicholas bought it in 1896.

He and his wife Ella had the Queen Anne elements added to the house in 1898.

The house features a three-story corner tower, prominent front porch, two balconies, and a stained glass window on the main facade.

It was listed on the National Register of Historic Places in 2017.