Question: Which company, headed by Thomas Tull, produced the 2013 film that was the first installment in the DC Extended Universe?
Context: Thomas Tull (born 1970) is an American businessman and film producer.  He is the former chairman of the Board and chief executive officer (CEO) of Legendary Entertainment.  His firm has produced and/or financed several major motion pictures, including "The Dark Knight Trilogy", "The Hangover" and its sequels, "300", "Man of Steel" and others. Justice League is an upcoming American superhero film based on the DC Comics superhero team of the same name, distributed by Warner Bros.  Pictures.  It is intended to be the fifth installment in the DC Extended Universe (DCEU).  The film is directed by Zack Snyder and written by Chris Terrio and Joss Whedon, from a story by Snyder and Terrio, and features an ensemble cast that includes Ben Affleck, Henry Cavill, Gal Gadot, Jason Momoa, Ezra Miller, Ray Fisher, Ciarán Hinds, Amy Adams, Willem Dafoe, Jesse Eisenberg, Jeremy Irons, Diane Lane, Connie Nielsen, and J. K. Simmons.  In "Justice League", Batman and Wonder Woman assemble a team consisting of Flash, Aquaman, and Cyborg to face the catastrophic threat of Steppenwolf and his army of Parademons. The Justice League Universe (JLUDCEUUJLDCE), more commonly known by its unofficial name as the DC Extended Universe (DCEU), is an American media franchise and shared universe, centered on a series of superhero films distributed by Warner Bros.  Pictures, based on characters that appear in publications by DC Comics.  The shared universe, much like the original DC Universe in comic books, was established by crossing over common plot elements, settings, cast, and characters.  The films have been in production since 2011 and in that time Warner Bros. has distributed four films with more than ten in various stages of production.  The series has grossed over $3.1 billion at the global box office, currently making it the seventeenth highest-grossing film franchise. Suicide Squad is a 2016 American superhero film based on the DC Comics antihero team of the same name, distributed by Warner Bros.  Pictures.  It is the third installment in the DC Extended Universe (DCEU).  The film is written and directed by David Ayer and stars an ensemble cast featuring Will Smith, Jared Leto, Margot Robbie, Joel Kinnaman, Viola Davis, Jai Courtney, Jay Hernandez, Adewale Akinnuoye-Agbaje, Ike Barinholtz, Scott Eastwood, and Cara Delevingne.  In "Suicide Squad", a secret government agency led by Amanda Waller recruits imprisoned supervillains to execute dangerous black ops missions and save the world from a powerful threat, in exchange for reduced sentences. The Arrowverse is a shared fictional universe that is centered on television series airing on The CW, developed by Greg Berlanti, Marc Guggenheim, Andrew Kreisberg, Phil Klemmer, and Geoff Johns, based on characters appearing in publications by DC Comics.  The shared universe, much like the DC Universe in comic books or the cinematic DC Extended Universe, was established by crossing over common plot elements, settings, cast, and characters.  The Arrowverse stars Stephen Amell as Oliver Queen / Green Arrow, Grant Gustin as Barry Allen / Flash, Megalyn Echikunwoke as Mari Jiwe McCabe / Vixen, with an ensemble cast leading "Legends of Tomorrow", including Arthur Darvill as Rip Hunter, Caity Lotz as Sara Lance / White Canary, Brandon Routh as Ray Palmer / Atom, Dominic Purcell as Mick Rory / Heat Wave, with Victor Garber and Franz Drameh as Martin Stein & Jefferson "Jax" Jackson / Firestorm.  Russell Tovey stars as Ray Terrill / The Ray. Aquaman is an upcoming American superhero film based on the DC Comics character of the same name, distributed by Warner Bros.  Pictures.  It is intended to be the sixth installment in the DC Extended Universe (DCEU).  The film is being directed by James Wan, with a screenplay by Will Beall, from a story by Wan and Geoff Johns, and stars Jason Momoa, Amber Heard, Patrick Wilson, Willem Dafoe, Yahya Abdul-Mateen II, Temuera Morrison, Dolph Lundgren, and Nicole Kidman. Batman v Superman: Dawn of Justice is a 2016 American superhero film featuring the DC Comics characters Batman and Superman.  Directed by Zack Snyder and distributed by Warner Bros.  Pictures, the film is the second installment in the DC Extended Universe (DCEU) following 2013's "Man of Steel".  It was written by Chris Terrio and David S. Goyer, and features an ensemble cast that includes Ben Affleck, Henry Cavill, Amy Adams, Jesse Eisenberg, Diane Lane, Laurence Fishburne, Jeremy Irons, Holly Hunter and Gal Gadot.  "Batman v Superman: Dawn of Justice" is the first live-action film to feature Batman and Superman together, as well as the first live-action cinematic portrayal of Wonder Woman, Aquaman, Flash and Cyborg.  In the film, criminal mastermind Lex Luthor manipulates Batman into a preemptive battle with Superman, whom Luthor is obsessed with defeating. Man of Steel is a 2013 superhero film featuring the DC Comics character Superman.  It is a British-American venture produced by Legendary Pictures, DC Entertainment, Syncopy Inc., and Cruel and Unusual Films, and distributed by Warner Bros.  Pictures.  It is the first installment in the DC Extended Universe (DCEU).  The film is directed by Zack Snyder, written by David S. Goyer, and stars Henry Cavill, Amy Adams, Michael Shannon, Kevin Costner, Diane Lane, Laurence Fishburne, Antje Traue, Ayelet Zurer, Christopher Meloni, and Russell Crowe.  "Man of Steel" is a reboot of the "Superman" film series that retells the character's origin story.  In the film, Clark Kent learns that he is a superpowered alien from the planet Krypton and assumes the role of mankind's protector as Superman, but finds himself having to prevent General Zod from destroying humanity. Wonder Woman is a 2017 American superhero film based on the DC Comics character of the same name, distributed by Warner Bros.  Pictures.  It is the fourth installment in the DC Extended Universe (DCEU).  The film is directed by Patty Jenkins, with a screenplay by Allan Heinberg, from a story by Heinberg, Zack Snyder, and Jason Fuchs, and stars Gal Gadot, Chris Pine, Robin Wright, Danny Huston, David Thewlis, Connie Nielsen, and Elena Anaya.  "Wonder Woman" is the second live action theatrical film featuring the titular character, following her debut in 2016's "".  Jenkins's role as director makes her the first female director of a studio superhero comic book live-action theatrical release film.  The film tells the story of Princess Diana, who grows up on the Amazon island of Themyscira.  After American pilot Steve Trevor crashes offshore of the island and is rescued by her, he tells the Amazons about the ongoing World War.  Diana then leaves her home in order to end the conflict, becoming Wonder Woman in the process. The DC Extended Universe is a media franchise and shared fictional universe that is the setting of superhero films independently produced by Warner Bros., based on characters that appear in DC Comics publications.
Answer: Legendary Entertainment