X-Men is an American superhero film series based on the fictional superhero team of the same name, who originally appeared in a series of comic books created by Stan Lee and Jack Kirby and published by Marvel Comics.
 20th Century Fox obtained the film rights to the characters in 1994, and after numerous drafts, Bryan Singer was hired to direct "X-Men" (2000) and its sequel, "X2" (2003), while Brett Ratner directed "" (2006).
Hela is a fictional character appearing in American comic books published by Marvel Comics.
 The Asgardian goddess of death is based on the Norse goddess, Hel.
 The ruler of Hel and Niflheim, the character has been a frequent foe of Thor.
 Debuting in the Silver Age of comic books, Hela first appeared in "Journey into Mystery" #102 and was adapted from Norse mythology by Stan Lee and Jack Kirby.
Sif is a fictional character appearing in American comic books published by Marvel Comics.
 The character is depicted commonly in association with the superhero Thor.
 Based on the Norse goddess Sif, she was created by Stan Lee and Jack Kirby and first appeared in "Journey Into Mystery" #102 (March 1964).
 As an Asgardian warrior and lover of Thor, Sif often accompanies Thor into battle.
 She has also battled alongside Balder, who has developed an unrequited attraction to her, as she never shows affection for anyone but Thor and certain individuals who have proved worthy to wield his hammer, Mjolnir, such as the noble alien warrior Beta Ray Bill and the mortal Eric Masterson.
 Sif has appeared in various media adaptations of Thor, including the 2011 Marvel Cinematic Universe film "Thor", its 2013 sequel "", and the television series "Agents of S.H.I.E.L.D.", in which she is portrayed by Jaimie Alexander.
Stan Lee Meets Superheroes was a limited Marvel Comics series in which comic book writer Stan Lee met one of the characters he has created in each issue.
 The series was written by Stan Lee himself and is used to celebrate his 65th year as a Marvel Comics employee.
 The series is marked for its tongue-in-cheek humor and the comic book characters' general dislike of Stan Lee.
 The series contains five issues in which Stan Lee meets Spider-Man, The Thing, Doctor Doom, Doctor Strange, and the Silver Surfer.
 Each issue also contained reprints of issues from each character's respective comic.
 An issue in which Stan meets Professor Xavier and Magneto was included with the DVD edition of "".
The Avengers are a fictional team of superheroes appearing in American comic books published by Marvel Comics.
 The team made its debut in "The Avengers" #1 (cover-dated Sept. 1963), created by writer-editor Stan Lee and artist/co-plotter Jack Kirby.
 The Avengers is Lee and Kirby's renovation of a previous superhero team, All-Winners Squad, that appeared in comic books series published Marvel Comics' predecessor Timely Comics.
Colonel Nicholas Joseph Fury is a fictional character appearing in American comic books published by Marvel Comics.
 Created by writer/artist Jack Kirby and writer Stan Lee, Fury first appeared in "Sgt. Fury and his Howling Commandos" #1 (May 1963), a World War II combat series that portrayed the cigar-chomping Fury as leader of an elite U.S. Army unit.
 A popular character over a number of decades, in 2011, Fury was ranked 33rd in IGN's Top 100 Comic Book Heroes, and 32nd in their list of "The Top 50 Avengers".
 He has sometimes been considered an antihero.
Goodman, Lieber, Kurtzberg & Holliway is a fictional law firm appearing in American comic books published by Marvel Comics.
 The firm is commonly depicted in the pages of the "She-Hulk" comic books - named after Marvel Founders Martin Goodman, Stan Lee, under his birth name Stanley Lieber, and Jack Kirby, using his birth name Jacob Kurtzberg.
 Created by Dan Slott, senior GLK&H law partner Holden Holliway first appeared in "She-Hulk" #1 (May 2004), where he hired the titular heroine to be a lawyer for his law firm, but as Jennifer Walters.
Quicksilver (Pietro Maximoff) is a fictional superhero appearing in American comic books published by Marvel Comics.
 The character first appeared in the comic book "X-Men" #4 (March 1964) and was created by Stan Lee and Jack Kirby.
 The character has since starred in two self-titled limited series, and has historically been depicted as a regular team member in superhero title "The Avengers".
Doom 2099 (Victor Von Doom) is a fictional anti-hero appearing in American comic books published by Marvel Comics.
 The character was primarily featured in the Marvel 2099 series "Doom 2099".
 The character is based on Doctor Doom, created by Stan Lee and Jack Kirby.
 The series was written by John Francis Moore for its first two years, and by Warren Ellis for its third.
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.

Question: Patrick Stewart plays which character in the film series based on the comic books created by Stan Lee and Jack Kirby?
Answer: Professor Charles Xavier