Boy Lornsen (7 August 1922 – 26 July 1995) was a German sculptor and author of children's literature, writing both in Standard German and in Platt.

Lornsen served as pilot and radio operator in the German Luftwaffe during World War II.

In 1967, he published his first children's book, about a boy who helps a robot with his homework, Robbi, Tobbi und das Fliewatüüt.

Lornsen's books were translated into numerous languages, including Greek, Japanese and Norwegian.

In 1980, his Jakobus Nimmersatt was adapted by Japan's Nippon Animation studio into a TV special, Nodoka Mori no Dobutsu Daisakusen (The Great Plan of the Animals of Placid Forest), directed by Yoshio Kuroda; the special was released in English under two different titles, Back to the Forest and Peter of Placid Forest.