WordNet (r) 3.0 (2006):

leading light
    n 1: a celebrity who is an inspiration to others; "he was host
         to a large gathering of luminaries" [syn: luminary,
         leading light, guiding light, notable, notability]

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "leading light":
   chief, electronics king, first-rater, genius, honcho, king, lead,
   luminary, master spirit, paramount, prima donna, principal,
   prodigy, star, superstar, top dog, topnotcher, virtuoso, wonder