Casey Junior is a fictional, anthropomorphic, young steam locomotive who is among the more memorable characters in the 1941 Disney animated feature film Dumbo, but has also appeared in other Walt Disney productions.
His name is a direct reference to Casey Jones, the famous railroad engineer who died in a train collision in 1900.
Casey is a tender engine hauling the circus train, and even has his own song. He appears frequently throughout the film, and is shown to be somewhat sapient. For example, when the Ringmaster calls “All aboard! All aboard!”, his whistle can be heard calling “All aboard! Let’s go!”