Synonyms for Kingpin (same or very similar meaning)
WordNet sense 1 (the most important person in a group or undertaking):
bigwig, top bananaWordNet sense 2 (bolt that provides a steering joint in a motor vehicle):
kingbolt, swivel pinWordNet sense 3 (the front bowling pin in the triangular arrangement of ten pins):
headpinFrom the ODE community, based on WordNetadd/edit