McLeod was born in Aberdeen, Scotland, on 23 December 1929. He obtained his PhD in 1959 under the supervision of
Edward Charles Titchmarsh at the University of Oxford. He was a junior lecturer in Mathematics at the
University of Oxford from 1956 to 1958, and a lecturer in mathematics at the
University of Edinburgh from 1958 to 1960. He then returned to Oxford to take up a Fellowship in Pure Mathematics at
Wadham College. In 1988 McLeod took up a professorship at the
University of Pittsburgh, where he remained until his retirement in 2007. McLeod married Eunice Third in 1956; they had three sons and a daughter. He died in England on 20 August 2014, aged 84. ==Awards and honours==