Mac Barnett is the author of many picture books including Chloe and the Lion and Guess Again! which TIME Magazine named the number 2 Picture Book of the year. He also writes the Brixton Brothers series of mysteries. Two of his collaborations with Jon Klassen, Extra Yarn and Sam and Dave Dig a Hole have won the Caldecott Honor. He is also the author of The Shape Trilogy, illustrated by Jon Klassen, A Polar Bear in the Snow, illustrated by Shawn Harris and Twenty Questions, illustrated by Christian Robinson. He lives in California, USA.