| Caleb Ayer | |
| Office1: | Secretary of State of Maine |
| Term1: | 1856 |
| Governor1: | Samuel Wells |
| Preceded1: | Alden Jackson |
| Succeeded1: | Alden Jackson |
| State Senate2: | Maine |
| State2: | Maine |
| District2: | York County |
| Term Start2: | 1847 |
| Term End2: | 1848 |
| Birth Date: | 22 May 1813 |
| Birth Place: | Newfield, Maine, U.S. |
| Death Place: | Cornish, Maine, U.S. |
| Party: | Democrat |
Caleb Robinson Ayer (May 22, 1813 – October 5, 1883) was an American politician from Maine.[1] Ayer graduated from Dartmouth College in 1834 and was admitted to the bar in 1838.[2] He was an associate of Nathan Clifford and moved to Cornish in York County in 1841. Six years later in 1847, Ayer was elected as a Democrat to the Maine State Senate and served as Senate President in 1848. In 1856, he served as the Secretary of State of Maine under Governor Samuel Wells.[3] He served as the York County Attorney General from 1868 to 1870. He died in 1883.[2] The Caleb R. Ayer House in Cornish is listed on the National Register of Historic Places.