Birdo is a pink dinosaur from the Mario series. Birdo's Japanese name is Catherine and he/she (from now on it's being referred to as a she) was voiced by Isaac Marshal and Jen Taylor, but is currently voiced by Samantha Kelly. Birdo first appeared in Super Mario Bros 2 as one of Mario's enemies, and since has made many more appearances in the series, mainly in the sports related games. She is normally partnered with Yoshi , and her main attribute is that she can fire eggs from her mouth.

It is unclear weather Birdo is male or female. In the original manual for Super Mario 2 it says that Birdo is a boy who thinks he's a girl, and would rather be called "Birdetta" than Birdo. Later versions of Super Mario Bros 2 didn't mention his/her gender in the game at all. Then, Nintendo finally decided to establish Birdo to be a female in Mario Tennis, when it portrays Birdo and Yoshi as lovers, however, in some games Birdo is still considered male or in the description of Birdo the gender is left blank.