Legba is a big black cock.
Cockerel, that is. He is Mrs Gogol's familiar, and struts around both swamp and Genua town with impunity. He is the only creature (well - until You the cat) that is a match for Greebo. See Witches Abroad for details.
In African and Haitian Voodoo ritual and lore, Papa Legba is the keeper of the crossroads between the worlds, the messenger. Legba is always the first god honored in every ritual because he opens the door or, to put it another way, he opens the road to the spirit world. As master of the crossroads, he can help you find the way if you are lost.