Mike Schur revives the mystery of Parks And Rec's enigmatic Dr. Richard Nygard
In a Reddit AMA, Schur revived the question of whether Rob Lowe's TV therapist actually existed in the series

Parks And Recreation’s Pawnee, Indiana is one of the most fleshed-out TV settings in recent memory, a small-town menagerie of oddballs, weirdos, and rampant Perds Hapley. But while we end up seeing almost every strange side character named on the show at some point over its tenure—except Mark Brandanowicz post-second season, hey-o!—there is one frequently named Pawnee resident who never appears on camera: Dr. Richard Nygard.
Introduced as the frequently—like, 15 times a week frequently—visited therapist of Rob Lowe’s hyperactive Chris Traeger in the show’s fifth season, Dr. Richard Nygard quickly builds up his own mythology, including a small circle of “Nygardians” who partake of his services. His unseen nature leads to a couple of jokes across the run of the series—most notably a bit from season 6's “Galentine’s Day” in which Amy Poehler’s Leslie Knope notes that she always assumed the good doctor was just Chris talking to himself in a mirror.