Zach Grenier (born in 1954) is an American actor renowned for his prolific career as a character actor, specializing in supporting roles. He is known for portraying intelligent, authoritative, and often enigmatic or morally ambiguous characters, ranging from lawyers to government figures, corporate executives to men of power.

Among his most memorable film performances are Richard Chesler, Edward Norton's boss, in David Fincher's *Fight Club* (1999), Detective Paul Avery in *Zodiac* (2007), another Fincher film, and the role of Eddie in the blockbuster *Twister* (1996). He also left his mark in films such as *Donnie Brasco* (1997), *Swordfish* (2001), and *Ride with the Devil* (1999).

Grenier brings to his roles an intense presence and a measured performance, making his characters, even minor ones, immediately recognizable and impactful.