You and I share a secret. We both know how easy it is to kill someone. That ultimate taboo - it doesn't exist outside our minds.
~ Finch, to Will Dormer

Walter Finch is the main antagonist of the 2002 psychological mystery-thriller film Insomnia.

He was portrayed by the late Robin Williams, who also portrayed Rainbow Randolph in Death to Smoochy, Seymour "Sy" Parrish in One Hour Photo and Merritt Rook in the Law & Order: Special Victims Unit episode "Authority".


Walter Finch is an author of a series of crime novels. After a teenage fan named Kay comes to visit him, he becomes a mentor to her - all while harboring sexual feelings for her. One night, Kay comes to see him after having a fight with her abusive boyfriend Randy, and in a moment of weakness he kisses her. When she laughs at him, he flies into a rage and slaps her. She screams, and Finch beats her to death. To hide evidence of her murder, he clips her nails to remove his DNA, cleans the wounds he inflicted, and throws her body in a dump.

Detective Will Dormer tracks the killer at a shack in a misty forest, but as Finch tries to escape, Dormer accidentally shoots his partner Hap. Finch sees this and, later that night, calls Dormer, who feels so guilty for killing his partner that he can't sleep. Finch blackmails Dormer into framing Randy for Kay's death. He rationalizes murdering Kay as "an accident" that "just turned out that way". He also rationalizes framing Randy by saying that he will kill someone eventually, so putting him in prison is actually a public service. Dormer is disgusted, but reluctantly follows through with the plan by planting evidence on Randy. For his part, Finch submits to a police interrogation and supplies answers Dormer gave him in order to allay suspicion. Afterward, Dormer and Finch get into a violent argument in which Finch says they are just the same.

However, after rookie detective Ellie Burr discovers the truth about Dormer, he admits what really happened and goes to take out Finch in his shack by a lake. As Finch tries to kill both detectives, Dormer arms himself with a shotgun and sneaks up on Finch during the gunfight. After a struggle, they both end up shooting each other. Dormer is mortally wounded while Finch is killed instantly, and his body falls into the water below and sinks into the darkness.