Adam Michael Rex is an American illustrator and author of children's books, hailing from Tucson, Arizona. Born on May 16, 1973, Adam grew up in Phoenix, Arizona, as the middle of three children. While he was neither the smart one (his older brother) nor the cute one (his younger sister), he was the one who could draw.

Adam took a lot of art classes as a child, striving to improve his drawing skills, and began painting at the age of 11. He later moved to Tucson to further hone his skills, earning a BFA from the University of Arizona, and met his physicist wife, Marie, who he describes as both the smart and cute one.

Adam is known for his nearsightedness, lack of sports skills, and learning to play the theremin. Despite sometimes needing a shave, he can carry a tune, although it might get dropped and stepped on occasionally. He admits to never remembering anyone's name until he's heard it at least three times.

Adam is the author and illustrator of more than forty books for children, including New York Times bestselling picture books like Frankenstein Makes a Sandwich and School’s First Day of School, with illustrator Christian Robinson. His work has been adapted for film and television, and he has received accolades including the Margaret Wise Brown Prize in Children's Literature and the National Cartoonists Society Book Illustration Award. His debut novel was shortlisted for the Andre Norton Award for Young Adult Science Fiction and Fantasy.

Previously, Adam created art for games like Dungeons & Dragons and Magic: The Gathering, and he sometimes still does. He currently resides in Tucson, Arizona, with his dog, son, and wife. Steve Malk represents Adam's book work.