Guest Stars James Doohan voices Lt. Montgomery "Scotty" Scott Majel Barrett Roddenberry voices Nurse Christine Chapel Majel Barrett Roddenberry voices Amanda Grayson Majel Barrett Roddenberry voices Gray James Doohan voices Guardian of Forever James Doohan voices Thelin James Doohan voices Bates James Doohan voices Vulcan Healer James Doohan voices Erikson James Doohan voices Aleek-Om Uncredited Mark Lenard voices Sarek Billy Simpson voices Young Spock Keith Sutherland voices Young Sepek