Ulf Gottfrid Stark (12 July 1944 – 13 June 2017) was a Swedish author and screenwriter (he adapted several of his own books for film and wrote the screenplay for the 1999 film Tsatsiki, morsan och polisen).
Stark has collaborated with the illustrators Anna Höglund and Mati Lepp.
From 1989 to 1998 he was an elected member of the Swedish Academy for Children's Books.
In 1998 he received the Nordic Children's Book Prize.
Stark died 13 June 2017 in Stockholm, Sweden.
Stark was born and grew up in Stureby, Stockholm Municipality, which place features in several of his books. Stark's interest in writing started early; during his time at secondary school he was introduced to writing by his classmate Peter Curman, and in 1964 he wrote his first poetry Ett hål till livet. Following this, Stark's interest in writing for a career was greatly encouraged.