Betsy Reilly Lewin (born May 12, 1937) is an American illustrator from Clearfield, Pennsylvania. She studied illustration at Pratt Institute. After graduation, she began designing greeting cards. She began writing and illustrating stories for children's magazines and eventually children's books. She is married to children's book illustrator Ted Lewin and with him has co-written and illustrated several books about their travels to remote places, including Uganda in Gorilla Walk and Mongolia in Horse Song, as well as How to Babysit a Leopard: and Other True Stories from Our Travels Across Six Continents (Roaring Brook Press, 2015). She is arguably best known for the Caldecott Honor Book Click Clack Moo: Cows that Type.

Here is a partial list of recent exhibits featuring Betsy's works:

Exhibition: "Around the World with Ted and Betsy Lewin" October 30 - December 2, 2008

Exhibition: "Adventures With Ted and Betsy" June 1 through June 11, 2005

Exhibition: "NCCIL Traveling Show"Feb. 12 through May 1, 2005

Exhibition: "Ted and Betsy Lewin's World of Picture Books" March 4–30, 2004

Exhibition: "Travels with Ted and Betsy Lewin" Featured 78 original illustrations from many of their books.

Exhibition: "Adventures with Ted and Betsy", Abilene, TX, Watershouse, Germantown, MD, Wichita Falls, TX