Jef Czekaj is a cartoonist, children's book author and illustrator, and musician.

His comic, Grampa and Julie: Shark Hunters, ran in Nickelodeon Magazine for more than 10 years. A collection of the first three years of the comic was published with the help of a Xeric Foundation Grant and distributed by Top Shelf.

He has illustrated 3 books, and written and illustrated 3 picture books and one graphic novel. His books, Hip and Hop, Don't Stop!, Cat Secrets, and, The Circulatory Story, were all chosen as Junior Library Guild selections. Cat Secrets was a finalist in GoodReads Best Books of 2011.

He DJs for an award-winning hip-hop group under an assumed name.

Jef lives and works in Somerville, MA.