James O'Neill (September 3, 1847 – June 9, 1929) was an American lawyer, jurist, and Republican politician.

Earlier, he had served one term in the Wisconsin State Assembly, representing Clark County.

In 1873, he moved to Neillsville, Wisconsin at the invitation of his uncle James O'Neill and practiced law.

He practiced law with Spencer M. Marsh until he was elected Wisconsin Circuit Court judge in 1897 serving until 1922.

This article about a Republican Party member of the Wisconsin State Assembly born in the 1840s is a stub.