Karl Hugo Prüter (July 3, 1920 – November 18, 2007) was an Old Catholic bishop in the United States. Pruter was raised in a Lutheran church and served as a Congregationalist minister under the name of Hugo Rehling Pruter, Sr., from 1945 to 1958. In the Congregationalist Church, he was one of the leaders of the liturgical movement in the church during the late 1940s and early 1950s. He was also an opponent of the merger of the Congregational Christian Churches with the Evangelical and Reformed Church to form the United Church of Christ, begun in 1957 and concluded in 1961. As a continuing Congregationalist, he led his church and several other Midwest Congregational churches to reject the merger and form a new body, the Central Association of Congregational Christian Churches.