Donkey

History
Donkeys were, like all other Narnian creatures, created by Aslan at the Birth of Narnia, and two of them (a male and a female) were given speech. Donkeys are presumed to have participated in all of the major events and battles of Narnia, but histories only mention two donkeys specifically.

Rabadash the Ridiculous
After Prince Rabadash's dishonorable attack on Anvard, Aslan turned him into a dumb donkey because of his pride and anger with King Lune. Rabadash remained a donkey until the next year's Autumn Festival in Tashbaan, where he resumed his usual shape in front of thousands of Calormenes. Because of the affair, the Calormenes called him "Rabadash the Ridiculous" behind his back and after his death.

Puzzle
Puzzle was a friend of Shift the Ape before and during the Calormene Conquest during the reign of King Tirian. Because Shift was by far the cleverer of the two, he was able to convince the well-meaning Puzzle to participate in the False Aslan Affair by dressing up in a lion-skin and pretending to be Aslan. Puzzle's conscience was uneasy despite the Ape's persuasiveness, and he joined Tirian's side midway through the deception. When Aslan ended the Narnian world, Puzzle came in at the stable door to Aslan's Country with all of the other Narnians who loved Aslan. When he finally met the Lion, he was quite afraid and ashamed of himself. As recorded by Lewis,

"The Lion bowed down his head and whispered something to Puzzle at which his long ears went down, but then he said something else at which the ears perked up again. [No one could] hear what he had said either time."

- C. S. Lewis