Marian Blank Horn (born 1943) is a senior judge of the United States Court of Federal Claims.

She was an assistant district attorney in Bronx County, New York, and then entered private practice as a litigator with the firm of Arent, Fox, Kintner, Plotkin and Kahn.

[1] From 1973 to 1975, Horn was a project manager for a Study of Alternatives to Conventional Criminal Adjudication, and an adjunct professor at American University's Washington College of Law.

[2] From 1981 to 1986, she worked in the United States Department of the Interior, where she assisted the Associate Solicitor and helped administer the Surface Mining Control and Reclamation Act of 1977.

[3] In 1986, President Ronald Reagan appointed Horn as judge of the United States Court of Federal Claims.