Lucas Conrad Elmendorf (1758 – August 17, 1843) was a United States representative from New York.
Born in Kingston, New York, he graduated from Princeton College in 1782, studied law, and was admitted to the bar in 1785 and practiced.
He declined to be a candidate for renomination in 1802 and was a member of the New York State Assembly in 1804 and 1805.
He died in Kingston in 1843; interment was in the crypt of the First Dutch Church.
His 2nd great-niece, through his sister, Blandina Elmendorf Brodhead, was Cordelia Phythian, who married Joel R. P. Pringle.