Pelfrey was a Federation ambassador who worked with the Bureau of Interplanetary Affairs in the 2290s. In 2292, Pelfrey was involved in negotiations of rubindium mining rights with the Frunalians. However, he found Jalira Tren, the Frunalian ambassador, rather difficult to deal with. In 2293, he was replaced by Ambassador Spock. (TOS novel: Crucible: The Fire and the Rose).