William "Billy" Twofeathers is the Native American resident railroad engineer on the Indian Valley Railroad and driver of the Rainbow Sun, as well as the handyman at Shining Time Station, who like his predecessor Harry Cupper, has a knack for repairing just about everything.
Billy is a reliable, outspoken and well-grounded individual who is proud of his Lakota heritage and culture. He is a talented artist, singer and guitar/flute player.
His grandfather, William Twofeathers also worked at Shining Time Station during its early years. Billy is the uncle of Kit Twofeathers, whose now-deceased father was Billy's brother. Billy is also known to have three uncles.
Billy often helped Stacy and acted as her assistant.
- Season 2 - Scare Dares, Oh, What a Tangled Web, The Magic is Believing, Win, Lose or Draw, Sweet and Sour, Achoo, A Dog's Life, Field Day, Wrong Track, Washout, Crackpot, Yabba, Yabba, Yabba, Nickel in a Pickle, Stop the Press, He Loves Me, He Loves Me Not, Double Trouble, Is Anybody There?, Do I Hear, Jingle, Jingle, Jingle, and All's Fair
- Season 3 - Becky Makes a Wish, Schemer's Alone, Bully for Mr. Conductor (mentioned), Stacy Cleans Up (mentioned), Billy Saves the Day, Billy's Party, Fortune Teller Schemer (mentioned), Billy's Runaway Train, Mr. Conductor's Evil Twin, Bad Luck Day at Shining Time Station, Mr. Conductor's Fourth of July, Stacy Forgets Her Name (flashback), Schemer's Special Club, Mr. Conductor's Movie, Dance Crazy, Mysterious Stranger, Mr. Conductor Gets Left Out, Mr. Conductor's Big Sleepwalk, Stacy Says No, and How the Station Got Its Name
- The Family Specials - Once Upon a Time, Second Chances, One of the Family and Queen for a Day (mentioned)
- Mr. Conductor's Thomas Tales - Wish You Were Here (mentioned)
- Thomas and the Magic Railroad
- Rick Siggelkow stated in an interview that Billy's creation was partially inspired by his own Native American descent. He also stated that he saw Billy Twofeathers as a good role model for boys.
- He and Stacy had a much larger role in the original cut of Thomas and the Magic Railroad, as they try to figure out how Shining Time has begun to change after the gold dust's disappearance.
- His voice was dubbed by Kiyohiko Ozaki in the Japanese dub of Thomas & the Magic Railroad and by Aryeh Cherner in the Hebrew dub.