Paul LeRoy "Roy" Siemiller (September 4, 1904 – June 2, 1993) was an American labor union leader.
He then traveled to undertake short-term work until he settled in Atlanta and completed an apprenticeship as a machinist.
In 1937, he began working full-time for the international union, organizing workers on the Pennsylvania Railroad.
He was the American Federation of Labor delegate to the International Labour Organization in 1947, and in 1948, he was elected as a vice-president and executive board member of the IAM.
He retired from his union posts in 1969, becoming vice-president for labor relations of the National Alliance of Businessmen.