Bob Cowley Riley (September 18, 1924–February 16, 1994) was the Democratic Governor of Arkansas for ten days in 1975.

Bob Riley was born in Little Rock, Arkansas and attended public schools there. He served in the United States Army during World War II. He graduated from the University of Arkansas in 1950 and obtained his master's degree from the University of Arkansas in 1951.

Riley served as a member of the Arkansas House of Representatives from 1946 to 1950.

Riley taught at Little Rock University from 1951 to 1955, and received his doctorate in education from the University of Arkansas in 1957.

He then took a post at Ouachita Baptist University at Arkadelphia. He served on the Arkadelphia City Council from 1960 to 1966 and served as mayor in 1966 and 1967.

He served as Lieutenant Governor of Arkansas from 1971 to 1975. Riley became acting governor of Arkansas in 1975 to serve out the final 10 days of the unexpired term of then Senator-elect Dale Bumpers.

Riley taught at Ouachita Baptist University until his death on February 16, 1994.