Books like ricky ricotta's mighty robot adventures

Ricky Ricotta's Mighty Robot is a series of children's graphic novels written by Dav Pilkey (best known for his Captain Underpants books) and first seven books illustrated by Martin Ontiveros and all nine books, including two long-awaited sequels, illustrated by Dan Santat. In each book, Ricky Ricotta, a mouse, with the help of his mighty robot, saves the world from an evil villain. Also, the books each have an alien creature from a different planet in order from closest-to-sun to farthest-from-sun including Earth, as the villain of the first book is from Earth. The reader could see the villains being jailed in each series and later notice the familiar villains from previous books.

The first three books were originally published as Ricky Ricotta's Giant Robot. Dav Pilkey stopped using the word Giant in the year 2002 after many young fans pointed out that the Robot really isn't a giant. He's just 12 times taller than a mouse, so he's really only about two and a half feet tall. Many young readers suggested the adjective "Mighty" instead, so after careful consideration, Pilkey changed the title on all the books.