[2] At that young age, he promptly wrote to Walt Disney Productions to express his interest in working there, and received back a form letter[3] which he has kept ever since.

"[4] After graduating from Theodor-Heuss Gymnasium (secondary school) in Dinslaken, where he was taught by the artist and art teacher Alfred Grimm,[5] he studied graphic design at the Folkwang Hochschule in Essen, Germany.

[11] Deja is best known as the supervising animator of some of the most memorable Disney villains: Gaston in Beauty and the Beast,[12] Jafar in Aladdin,[13] Scar in The Lion King[14] and Queen Narissa in Enchanted.

[16] In 2015, Deja authored The Nine Old Men: Lessons, Techniques, and Inspiration from Disney's Great Animators ISBN 978-0415843355 published by Focal Press.

[19][20] A Members Only Preview of the exhibition which included a special talk with Deja, Darleen Carr, Floyd Norman and Bruce Reitherman took place on June 22, 2022.

[21] Deja also wrote an extensive companion book for the exhibition which was originally slated to be published by Weldon Owen on September 20, 2022,[22] before it was changed to November 1, 2022.