Alvan Clark (March 8, 1804 – August 19, 1887), born in Ashfield, Massachusetts, was an American astronomer and telescope maker.

He started as a portrait painter and engraver (c.1830s–1850s), and at the age of 40 became involved in telescope making.

Using glass blanks made by Chance Brothers of Birmingham, England, and Feil-Mantois of Paris, France, his firm Alvan Clark & Sons ground lenses for refracting telescopes.

Although not specifically searching for double stars, he did make a number of discoveries while testing his completed telescope objectives,[1] including Mu Herculis, 8 Sextantis, and 95 Ceti.

Exclusive license to this patent (1,565 of April 24, 1840) was made to Edwin Wesson, brother of Daniel B.