Orren D. Casselman (November 3, 1862 – ) was an Ontario merchant and political figure. He represented Dundas in the Canadian House of Commons from 1917 to 1921 as a Unionist member.
He was born in Chesterville, Canada West, the son of James C. Casselman, and was educated in Morrisburg and Hamilton. He taught school for two years before opening a general store in Chesterville. In 1905, he married Alin Sanders. Casselman was a recruiting officer and served overseas during World War I. He was defeated in the 1921 general election.
His half-brother William H. Casselman served in the Ontario provincial assembly.