Aernout van Lennep (23 February 1898 – 17 December 1974) was a Dutch horse rider.
He competed in eventing at the 1932 Summer Olympics and won a team silver medal, finishing ninth individually.Van Lennep was a career artillery officer, and won the Dutch military championships in 1931.
He was a prisoner of war in Germany during World War II, and later became a lieutenant colonel in the 1950s.