Guido (a.k.a. Mysterious Guido by the official website and by fans), voiced by Rob Paulsen, is a character in the Land Before Time films and television series. He is a Microraptor gui, and first appeared in The Land Before Time XII: The Great Day of the Flyers. Although rumored to be multicolored, his feathers are presented in warm shades of green and yellow, mostly Jade. He has never seen another creature like himself. He is more of a comic relief character than previous guest characters. He later appears in "The Hermit of Black Rock", when he learns how to truly fly. Prior to that episode, he met Chomper and Ruby while he was babysitting Tricia. Guido refers to Chomper as "Chomper the Friendly Sharptooth" (a parody of Casper the Friendy Ghost). Guido and The Rainbow Faces are the only theropods on The Great Valley. Ducky says Guido a sharp tooth when Petrie see Guido that he think that he was scare. He does not like plants but he eats worms (common diet between most avian dinosaurs). He was the only Glider (Other types with only one member of a species showing up are Sharpbeaks, Thicknoses, and Hidden Runners) in The Land Before Time. A Spinosaurus almost ate Guido. He sees also a skeleton of a Tyrannosaurus in the Mysterious Beyond.
- Among the Land Before Time characters, Guido is one of three characters to end up in the mouth of a Sharptooth, the other two are Littlefoot and Petrie.