Dr. Carlyle is a vascular surgeon at Princeton-Plainsboro Teaching Hospital. He is an unseen character in the Season 8 episode Chase.
While Chase is arguing with the rest of the team about whether he should be allowed to operate on Moira despite their relationship, he points out that Carlyle and another qualified surgeon, Kapur, are both out of the hospital and the only other qualified surgeon available, Reilly, is less experienced than he is with this procedure.