Matthew Michael Carnahan (sometimes identified as Matt Carnahan) is an American screenwriter who wrote the feature film The Kingdom (2007), and the film adaptation of the hit BBC television drama serial State of Play. Carnahan also wrote the screenplay for Lions for Lambs for United Artists. His brother is Joe Carnahan, who wrote and directed Narc (2002), Smokin' Aces (2006) and The A-Team (2010).
Critical reaction to Carnahan's work has been mixed. The Kingdom averaged a 56 on Metacritic. Rotten Tomatoes lists the film with 53% of critics giving the film positive reviews, based on 120 reviews. Lions for Lambs received generally negative to mixed reviews from critics. On the review aggregator Rotten Tomatoes, 27% of critics gave the film positive reviews, based on 133 reviews. On Metacritic, the film had an average score of 47 out of 100, based on 33 reviews.
He worked on the screenplay for the zombie film World War Z (2013).
He also wrote the screenplay for the film adaptation of Nemesis with his brother Joe Carnahan.