top dog

from WordNet (r) 3.0 (2006)

top dog
    n 1: a person who is in charge; "the head of the whole
         operation" [syn: {head}, {chief}, {top dog}]

from Moby Thesaurus II by Grady Ward, 1.0

60 Moby Thesaurus words for "top dog":
      A per se, ace, boss, champ, champion, chief, commander,
      conquering hero, conqueror, conquistador, dean, defeater, doyen,
      doyenne, easy winner, electronics king, fugleman, genius, head,
      hero, high priest, higher-up, honcho, important person, king,
      kingfish, kingpin, laureate, lead, leader, leading light, luminary,
      master, master spirit, nonpareil, pancratiast, paragon, paramount,
      personage, prima donna, principal, prodigy, ruler, runner-up,
      senior, shoo-in, star, subduer, subjugator, superior, superman,
      superstar, sure winner, the greatest, the most, triumpher,
      vanquisher, victor, virtuoso, winner