Elias Deemer (January 3, 1838 – March 29, 1918) was a Republican member of the U.S. House of Representatives from Pennsylvania.

During the Civil War, he enlisted in July 1861 as a private in Company E, One Hundred and Fourth Regiment, Pennsylvania Volunteers, and served until the middle of May 1862, when he was discharged because of disabilities.

Deemer was elected as a Republican to the Fifty-seventh, Fifty-eighth, and Fifty-ninth Congresses.

He resumed lumber operations in Pennsylvania, and at Deemer, Mississippi, an unincorporated town he founded, and which was named for him.

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