Mason R. Verger is a fictional character and the main antagonist of Thomas Harris' 1999 novel Hannibal, as well as its 2001 film adaptation and the second and third seasons of the TV series Hannibal. In the film, he is portrayed by Gary Oldman, while in the TV series he is portrayed by Michael Pitt and Joe Anderson.

Mason Verger is introduced in the novel Hannibal as a wealthy, sadistic pedophile who was paralyzed and severely disfigured during a therapy session with Dr. Hannibal Lecter. He plans gruesome revenge against Lecter, which sets the novel's plot in motion. The novel and TV series also portray his dysfunctional relationship with his sister Margot, whom he subjects to years of emotional and sexual abuse.

In Red Dragon, Will Graham mentions that Hannibal Lecter has nine known murder victims, while two other victims survived, one of whom is "on a respirator at a hospital in Baltimore." This is the earliest reference to Mason, though he is not named or further detailed until Hannibal.

Mason Verger is the scion of one of Baltimore, Maryland's most wealthy, politically connected families. His ancestors founded a meatpacking company that dated back to the American Civil War, and Mason's father, Molson, had expanded the company into an empire by the time of Mason's birth.

Mason takes pleasure in acts of cruelty and sexual violence, including torturing animals and molesting children. He also performs autoerotic asphyxiation, and enjoys collecting children's tears with sterile swabs and flavoring his martinis with them. At one point he befriends Idi Amin, with whom he claims to have re-enacted the crucifixion of Jesus by nailing a migrant worker to a cross. Publicly, he claims to be a born-again Christian, and operates a Christian camp for underprivileged children—whom he molests. As a teenager, Mason raped his sister, Margot, who went into therapy with Lecter to deal with the trauma. Lecter suggested that it would be cathartic for her to kill her brother.

Verger is eventually arrested for several counts of child molestation, but thanks to his family's political connections he is sentenced to community service and court-mandated therapy in lieu of prison time. Lecter serves as his court-appointed psychiatrist. During one of their sessions, Lecter invites Mason to demonstrate autoerotic asphyxiation, then gives him a cocktail of psychedelic drugs disguised as an amyl popper and suggests that he peel off his own face with a piece of broken mirror. In a state of drug-induced euphoria, Mason complies, and feeds the pieces to his dogs, except for his nose, which he himself eats. Lecter then tightens the noose around Mason's neck so hard it breaks his spine. Mason survives the ordeal, but is left severely disfigured—with skin grafts covering the lost portions of his face—blind in his right eye, paralyzed from the neck down, and dependent on a ventilator to breathe.

Lecter is arrested soon afterward for committing a series of murders, and Mason tries to influence the resulting trial to make sure Lecter receives the death penalty. When Lecter is instead found not guilty by reason of insanity and institutionalized, Mason begins plotting to feed Lecter alive to a pack of wild boars, specially bred for the purpose.

After his disfigurement, Mason becomes a recluse, rarely leaving Muskrat Farm, his country estate. He nevertheless indulges in whatever paraphilias his disability allows, such as getting sexual gratification from making children cry. Verger's only sources of human contact are his assistant, Cordell—a fellow sex offender—and Margot, who works for Mason as a bodyguard. Margot despises her brother, but stays in his employ to persuade him to donate his sperm to her partner, Judy Ingram, so they can conceive a child. Mason strings her along, knowing she cannot leave if she wants to see her share of the Verger family fortune; their father had disinherited her when she came out as a lesbian, and willed his estate to any future heir Mason might have.