Zak Penn (born March 23, 1968) is an American screenwriter. Penn wrote and directed Incident at Loch Ness and The Grand, wrote the script for The Incredible Hulk, co-wrote the scripts for X2 and X-Men: The Last Stand, and the story for The Avengers. With Michael Karnow, Penn is the co-creator of the TV series Alphas on the Syfy network.

Penn was born in New York. He is the son of New York businessman and lawyer Arthur Penn, who led the acquisition of the Capital Markets Assurance Corporation from Citicorp. Zak Penn graduated from Wesleyan University in 1990. His screenplay for PCU was based on his experiences at the Eclectic Society house. Films that Penn has been involved in writing include Last Action Hero, X2, X-Men: The Last Stand, and Elektra. Penn wrote early drafts of Hulk, The Incredible Hulk, The Avengers, and Free Guy. Penn is also a jury member for the digital studio Filmaka, a platform for undiscovered filmmakers to show their work to industry professionals. In July 2012, Avatar Press released the first issue of Penn's first comic book, Hero Worship. The six-issue series is co-written with Star Wars: The Clone Wars screenwriter Scott Murphy and drawn by Michael DiPascale. It centres on Zenith, an indestructible hero who has fans following every disaster, trying to catch a glimpse of the ultimate celebrity and risking their own lives in the process. One fan becomes so obsessed that it leads to the development of his own powers. He directed the documentary film Atari: Game Over. Description above from the Wikipedia article Zak Penn, licensed under CC-BY-SA, full list of contributors on Wikipedia.