Question: Legion's father, Professor Charles Xavier and founder of the X-Men, was also know by what name?
Context: Legion (David Charles Haller) is a fictional superhero appearing in American comic books published by Marvel Comics.  He is the mutant son of Professor Charles Xavier and Gabrielle Haller.  Legion takes the role of an antihero who has a severe mental illness including a form of dissociative identity disorder, in which each of his alternate personas controls one of his many superpowers. X-Men: First Class (stylized onscreen as X: First Class) is a 2011 American superhero film, based on the X-Men characters appearing in Marvel Comics.  It is the fifth installment in the "X-Men" film series.  It is both a prequel and a soft reboot of the franchise, the film was directed by Matthew Vaughn and produced by Bryan Singer.  The story is set primarily in 1962 during the Cuban Missile Crisis, and focuses on the relationship between Professor Charles Xavier (James McAvoy) and Erik Lehnsherr / Magneto (Michael Fassbender), and the origin of their groups—the X-Men and the Brotherhood of Mutants, respectively, as they deal with the Hellfire Club led by Sebastian Shaw (Kevin Bacon), who is bent on world domination.  The film co-stars Rose Byrne, January Jones and Oliver Platt.  The film also introduces new actors to the series including Nicholas Hoult and Jennifer Lawrence who, like McAvoy and Fassbender, reimagine popular characters from the franchise (Beast and Mystique) that have already been established in previous films, namely the original trilogy. Cerebro (Spanish and Portuguese for "brain") is a fictional device appearing in American comic books published by Marvel Comics.  The device is used by the X-Men (in particular, their leader, Professor Charles Xavier) to detect humans, specifically mutants.  It was created by Professor X and Magneto, and was later enhanced by Dr. Hank McCoy.  The current version of Cerebro is called Cerebra, to be distinguished from the character of the same name.  Cerebro first appeared in "X-Men" #7 (1964). "New Worlds" was the third story arc from Grant Morrison's run on the Marvel Comics title New X-Men, running from issues #127-133.  In the aftermath of both the Genoshan genocide and Cassandra Nova's revelation of Charles Xavier's mutant powers, as well as his school's function as a mutant haven, the X-Men must try to broker peace amidst rising human/mutant tensions, while still combating the mutant threats arising worldwide.  This story arc not only dealt with the fallout of Genosha's destruction, but also began the psychic relationship shared by Cyclops and Emma Frost. Sage, also known as Tessa, is a fictional character in the Marvel Comics universe.  She has most often been associated with the X-Men and the Hellfire Club, whom she spied upon for Professor Charles Xavier. Lilandra Neramani is a fictional character appearing in American comic books published by Marvel Comics, most commonly in association with the X-Men.  She is the Empress, or Majestrix, of the Shi'ar Empire and shares a lifelong bond with the leader of the X-Men, Charles Xavier.  She and Xavier were married, but their marriage was annulled after the Cassandra Nova incident. The following is a list of theatre, film, and television credits for English actor Patrick Stewart.  He is known for his roles as Captain Jean-Luc Picard in the "Star Trek: The Next Generation" franchise and as Professor Charles Xavier in the "X-Men" film series.  He has also been the voice of Avery Bullock on "American Dad! " since 2005.  He won a Grammy Award in 1996 and is also a Tony, Emmy, and Golden Globe nominee. X-Men: Deadly Genesis is a comic book limited series published by Marvel Comics in late 2005 and early 2006.  The series was written by Ed Brubaker with interior art by Trevor Hairsine and covers by Marc Silvestri.  Starring the X-Men, this series celebrates the 30th anniversary of "Giant-Size X-Men" #1.  The plot deals with the X-Men looking for Professor Charles Xavier, who went missing after "House of M", as well as the appearance of a new, incredibly powerful mutant threat. Professor Charles Francis Xavier (also known as Professor X) is a fictional character appearing in American comic books published by Marvel Comics and is the founder and leader of the X-Men.  Created by writer Stan Lee and artist Jack Kirby, the character first appeared in "The X-Men" #1 (September 1963). "Bloodties", a 1993 Avengers/X-Men crossover that celebrates the 30th anniversary of both franchises.  It is a direct sequel to the X-Men "Fatal Attractions" storyline, in which Charles Xavier mindwipes Magneto.  The story of "Bloodties" details a civil war between the human and mutant populations of Genosha, incited by Magneto's former protogé Fabian Cortez.  Unaware of Magneto's incapacitation, Cortez attempts to shield himself from his former master's wrath by kidnapping Magneto's granddaughter Luna.  As Luna's father Quicksilver has strong ties to the X-Men and her mother Crystal is a member of the Avengers, both teams become involved in the Genoshan conflict.  The situation is further complicated by Magneto's lieutenant and self-proclaimed heir Exodus, who seeks to kill both Cortez for his betrayal and Luna for "disgracing" Magneto's line by being merely human.
Answer: Professor X