One of the persons who compose a social group (especially individuals who have joined and participate in a group organization) (noun)
WordNet. Princeton University. 2010.
Use "fellow member" in a sentence
"The Reverend Strangelove decided that the vicar would undoubtedly be hurt if he knew that a fellow member of the cloth had been in the village and had not called on him."
"I was tempted to ask how a fellow member of a club dedicated to noncommunication and misanthropy had managed to make known his peculiar talents, but I was distracted by Holmes, who had risen and was pawing vigorously through a desk drawer, finally to emerge with paper, pen, and a pot of glue."
"He was reminded of his omission, however, by a visit one evening from Mike Scanlan, the fellow member whom he had met in the train."