J.B. King is the only adult in the valley who believes in Mr. Conductor's existence, but has yet to see him. His conviction that Mr. Conductor is real stems from a childhood memory where, as a lonely boy waiting for his train to arrive at Shining Time Station, was whispered some comforting words by one of the Conductor Family. J.B. King always searches for signs of Mr. Conductor on occasion whilst visiting Shining Time Station, once finding his miniature Conductor's cap on the arcade floor. It is probably his belief that Mr. Conductor makes Shining Time Station a special place that prevents him from permanently closing the station.
A kind, stern and demanding man, J.B. King nonetheless is fair even as few of the shenanigans taking place in the station (especially by Schemer) try his patience on occasion.
- Season 1 - And the Band Played Off (voice only; not named), Agree to Disagree (mentioned), Just Wild About Harry's Workshop (mentioned), Promises, Promises, Word's Out (mentioned), Is This the End? and 'Tis A Gift
- Season 2 - Oh, What A Tangled Web, Achoo, Wrong Track (mentioned), Washout, Double Trouble, Jingle, Jingle, Jingle and All's Fair
- Season 3 - Becky Makes a Wish, Bully for Mr. Conductor, Billy's Party, Billy's Runaway Train, Mr. Conductor's Evil Twin, Stacy Forgets Her Name (stock footage; does not speak), Mr. Conductor's Movie, The Joke's on Schemer, Mr. Conductor's Big Sleepwalk and Stacy Says No
- The Family Specials - Once Upon a Time, Second Chances, One of the Family and Queen for a Day
- Schemer Presents! - How to Share (mentioned)