American film producer Mark Nielsen is best known for his association with Pixar Animation Studios. Besides serving as a production manager in the Oscar-nominated Up (2009), Nielsen has also worked as an associate producer in Cars 2 (2011) and the Oscar-winning Inside Out (2015).

In 2019, the producer bankrolled Toy Story 4 (2019), which featured Tom Hanks, Keanu Reeves, Joan Cusack and Tim Allen in pivotal voice roles.