The Dodo is an absolutely must-have character in any Wonderland collection, as it represents Lewis Carroll himself. It is said that, owing to his stammer, Carroll used to pronounce his real name DoDoDodgson. Whether or not this is true, when he gave a copy of Alice's Adventures Underground to his friend Robinson Duckworth, he inscribed it to "The Duck, from the Dodo."
The Baboon isn't mentioned in Carroll's text at all, but John Tenniel chose to portray one in his illustrations. (You can see it peering over the back of the Dodo.) Some critics have suggested that its inclusion might be a reference to Charles Darwin's theory of evolution, which was the cause of much debate at the time.
There are other animals who tumble into the pool, but we think that, if Tenniel can include whichever creatures take his fancy, then so can we! (And so can you.)
We love the Guinea Pigs which feature in the first book. They are only very minor characters (they don't even get to speak) but, like Alice, we like it when they have to be suppressed during the trial of the Knave of Hearts.
And there, the poem is interrupted...