Role in the film
Shortly after she turns Gus, Jacqueline, Matilda, and Teddy (the four mice Ella befriends in the movie) into white horses, the Fairy Godmother comes across two wild lizards and uses her magic to turn them into footmen. Although the lizards become human, they still have lizard characteristics, such as the green coloring on their outfits, long tongues, and an appetite for flies.
Upon arriving at the Palace, Ella admits her fears of not belonging to one of them (Mr. Lizard), saying that she is "only a Girl, not a Princess," to which he reassures her, stating that he's not a Footman, just a Lizard, and she should enjoy the night while it lasts. This helps to alleviate her concerns, allowing her to enjoy said night with Prince Kit.
After Ella leaves the palace in a rush, the scheming Duke and the Captain of the Guards give chase. During the chase, one of the footmen (who at this point got back their tails) uses his tail to flip a switch which closed a cast iron gate and stopped the Duke from chasing them.
The lizards are seen again at the end of the film where they are seen scurrying around the palace balcony (along with the four mice and Mr. Goose) when Ella and Kit are married as they address the public on a balcony.