Mark Fergus is an American screenwriter, film director, producer, and novelist best known for his long-standing creative partnership with Hawk Ostby. After beginning his career as a novelist, Fergus transitioned into screenwriting, where he established himself as one of Hollywood's leading writers of character-driven action and science fiction films. Together with Ostby, he received an Academy Award nomination for co-writing Children of Men (2006), widely regarded as one of the greatest science fiction films of the 21st century. The duo also wrote the screenplay for Iron Man (2008), helping shape the film that launched the Marvel Cinematic Universe and introduced Robert Downey Jr.'s iconic portrayal of Tony Stark. Their collaboration continued on films such as Cowboys & Aliens and they developed the critically acclaimed television series The Expanse, serving as executive producers and helping adapt James S. A. Corey's bestselling novels for television. Fergus is recognized for creating intelligent, emotionally grounded stories that blend large-scale spectacle with complex characters, making him an influential figure in modern science fiction and blockbuster filmmaking.