James O. McManus (born October 18, 1894) was an American politician.
Between 1939 and 1941 he was lieutenant governor of the state of Rhode Island.
He received his early education in the public schools of Coventry, Kent County, and then attended Warwick High School, after which he became a student at Bryant & Stratton’s Business College, Providence.
In 1938 he was elected Lieutenant Governor of Rhode Island alongside William Henry Vanderbilt III.
He was Deputy Governor and Chairman of the State Senate.