Alfred Thomas Agate (February 14, 1812 – January 5, 1846) was a noted American artist, painter and miniaturist.

Agate lived in New York from 1831 to 1838. He studied with his brother, Frederick Styles Agate, a portrait and historical painter. He later went on to study with Thomas Seir Cummings. By the late 1830s, Agate was exhibiting his work at the National Academy of Design in New York, and established himself as a skilled painter in oils. He was elected into the National Academy of Design as an honorary member in 1840.

Agate drew landscapes, portraits, and scientific illustrations. For much of his landscapes, Agate used a camera lucida, a device which projected the scene onto a piece of paper for purposes of tracing.