Capt. Thomas "Tommy" Gregson

Captain Gregson runs the NYPD homicide squad Sherlock Holmes gets attached to as part of his sobriety arrangement, and he's the one who has to decide, case after case, whether that arrangement is worth the trouble. He's pragmatic, unshowy, and skeptical of Holmes's methods only insofar as results don't back them up.

Elementary needed a captain who wasn't a rulebook obstacle or a rubber stamp, and Gregson is neither: he's a genuinely good detective who respects competence wherever he finds it. Aidan Quinn plays him with a tired, decent steadiness that makes his trust in Holmes feel earned rather than convenient, and his friendship with Holmes never curdles into cliché.