In 2008, artist Jason Polan set out on a virtually impossible mission: to document every person he encountered in his everyday life in New York City. Polan said of the resulting project, titled Every Person in New York, on his blog, “I will be drawing people every day and posting as frequently as I can. I draw in subway stations and museums and restaurants and on street corners. I try not to be in the way when I am drawing or be too noticeable.” The artist has gone on to draw thousands of portraits, many of which are compiled in his 2015 book, Every Person in New York (Chronicle), which features a foreword by comedian Kristen Wiig.

Polan created sketches of a number of children’s book authors and illustrators during this year’s BookExpo in New York City, and we’ve gathered a selection here.

Author Eoin Colfer signed Artemis Fowl books, as well as galleys of his forthcoming graphic novel, Illegal, co-written with Andrew Donkin and illustrated by Giovanni Rigano (Sourcebooks Jabberwocky).

Brian Selznick signed posters featuring his cover illustrations for the Harry Potter 20th anniversary editions, at the Scholastic booth.

Actor and author Taye Diggs appeared with illustrator Shane Evans for their new picture book, I Love You More Than... (Feiwel and Friends).

Jan Brett, author-illustrator of The Snowy Nap (Putnam).

James Patterson signed copies of his forthcoming books for young readers, including Cuddly Critters for Little Geniuses (Little, Brown/Patterson), which he co-wrote with his wife, Susan Patterson.

Nicola Yoon, author of The Sun Is Also a Star (Delacorte), and contributor to the YA anthology Fresh Ink (Crown).

Ruth Westheimer signed copies of her graphic novel-style autobiography, Roller-Coaster Grandma: The Amazing Story of Dr. Ruth (Apples and Honey).