Biff, who played the trampolining dog Buster in a John Lewis Christmas advert in 2016, has died.
The boxer became famous for his role in the festive video which saw the parents surprise their daughter with a trampoline for Christmas.
Biff, who celebrated his 12th birthday earlier this month, had started to have seizures which his owner revealed "we couldn't bring him back from, so we had to let him go".
The advert features a cover by Vaults of Randy Newman's One Day I'll Fly Away as the girl's father builds a trampoline in the garden on Christmas Eve.
Foxes, squirrels, a hedgehog and a badger later jump around on the trampoline - watched by Buster, who finally enjoys his own moment on the gift when the girl runs into the garden on Christmas Day.
Biff's owner, Jen Patten, said on social media: "Fly high our beautiful, special boy, we shall miss you forever.
"People say, he had a wonderful life with us, but in reality, we had a wonderful life with him.
"Biffy and I had a really special bond, and no matter what I asked of him, whether it would be new tricks, displays, meet and greets, or photos with children, adults and animals, he would happily oblige, with the patience of a saint.
"At home, he was pure joy, making us smile every day.
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"I don't know if you are aware but boxers are known as the clowns of the canines, and even though Biff would be professional at the right time, he never lost the ability to make us laugh.
"We shall miss him so much."