Out of all the auburn-colored lemurs, Willie is the darkest.
In the episode, "Empty is the Head," it is revealed that there has been a feud in his family going on for 10 generations.
Willie is the only named non-main character lemur to appear in the Madagascar film.
Willie, although an adult, is possibly younger than a lot of the other lemurs, since he acts more perky, has a young voice, has a skinny build, isn't married, and has a fast metabolism (which was shown as he was able to eat an inordinate amount of fruit and still look the same).
In Willie's binge-eating scene in the episode, "He Blinded Me With Science", his eyes suddenly turn from their normal green color to a light yellow.
Willie has a more or less propensity to steal, shown when his house was surrounded by Clover and the rest of the Ringtail Guard because he stole King Julien's boom box. Willie was beat up by King Julien, who then ran off with the boom box. He did, however, get upset when Pancho planned on stealing something.
King Julien cried when he thought Willie drowned.
Next to Mort, Willie has the highest voice out of all the male lemurs.
Willie was never called by his implied full name, "William" until Season 4 in The Good Book.
Willie is aware of his cowardly nature, and has even admitted it.
Willie's name is sometimes mistakenly spelled "Willy".
Willie's species is not specified.
Willie is number 3 on the kingdom's official sacrifice list.
His catchphrase "WE'RE ALL GONNA DIE!!!" was also used in The Nut Job films.
