Elwood Haynes "Bud" Hillis (March 6, 1926 – January 4, 2023) was an American politician. He served as a U.S. Representative from Indiana from 1971 through 1987 as a Republican. Hillis served in the United States Army in the European Theater with the rank of first lieutenant from 1944 to 1946. He retired from the Reserves in 1954 with rank of captain in the infantry. Bud Hillis was a younger brother to renowned choral director Margaret Hillis. Their father, Glen R. Hillis, was the Republican nominee for Governor of Indiana in 1940, losing by less than 4,000 votes. His maternal grandfather and namesake, Elwood Haynes, was an inventor and automobile pioneer.
Hillis was a resident of Windsor, Colorado. He died on January 4, 2023, at the age of 96.