Colonel Clay was a high-ranking military official of the Borginian Republic and the Chief of the Ibis Island complex. While he does not physically appear in any of the games, his ID card and several files mentioning his name can be found in Dino Crisis.
Very little is known about Clay's background, but it can be presumed that as a military commander he was heavily involved in the development of Third Energy and its possible offensive uses. A file found in the Medical Room stated that he planned to hold a meeting in the Strategy Room the night before the final Third Energy experiment. He was a regular patient to the medical staff and as such his card was left in the hands of the doctors.
After dinosaurs flooded the facility following the exchange it is unknown what happened to Clay, although it can be presumed that he was hunted down and eaten along with the majority of facility personnel.