patron saint

noun2

1. •
   A saint conceived as the patron (protector or supporter) of a particular place, group, person, or activity, for whom or for which his or her intercession is specially invoked.

   • My patron saint, St. John of Shanghai and San Francisco—also known as “St. John the Wonderworker”—is particularly noteworthy in this regard […] — 2016
2. •
   (figurative) An exemplar: an individual who exemplifies some trait or group.

   • Janet is the patron saint of procrastination. I'm thinking of erecting her a shrine of doughnut boxes in the breakroom.