Quaestor

Quaestor was a Q with substantial authority in the continuum, considered "the voice of the continuum" by a young version of Q. Along with Quinn, Q2 and Lady Q, he fought against 0 and his compatriots while Q stood on the sidelines and watched.

When Q took Jean-Luc Picard on a tour of his past to explain what dangers were lying beyond the Galactic Barrier, Picard saw Quaestor and noted that he had a striking resembalance to Picard himself, as well as sounding similar. Picard wasn't sure if this was intentional on the part of Q and suggested that Q has always viewed Picard as a sign of Authority.

(Novel: Q-Strike)