In 1965, he became an Imagineer. He wrote the scripts for several Disney theme park attractions, most notably Adventure Thru Inner Space, Pirates of the Caribbean, and the Haunted Mansion, as well as the lyrics to the theme songs of the latter two, "Yo Ho (A Pirate's Life for Me)" and "Grim Grinning Ghosts", respectively. He also wrote the lyrics of "Bear Band Serenade" for Country Bear Jamboree and "It's Fun to Be Free" for World of Motion.
Atencio died on September 10, 2017, six days after his 98th birthday.
|1953||Toot, Whistle, Plunk and Boom||Animator|
|1956||A Cowboy Needs a Horse||Layout Styling|
|1956||Jack and Old Mac||Character Styling|
|1957||The Truth About Mother Goose||Layout|
|1959||Noah's Ark||Character Movement/Styling|
|1961||The Parent Trap||Title Animation|
|1961||Babes in Toyland||Toy Sequence animator|
|1964||The Misadventures of Merlin Jones||Title Animation|
|1966||Winnie the Pooh and the Honey Tree||Story|