Paul Giamatti

Film Deaths

Private Parts (1997)
American Splendor (2003)
Cinderella Man (2005)
Shoot 'em Up (2007) [Hertz]: Shot in the chest in a shoot-out with Clive Owen in Paul's home, blowing a hole straight through his torso (after Clive first puts several bullets between his broken fingers than sticks them beside a lit fireplace, setting them off). (Thanks to Adam)

The Haunted World of El Superbeasto (2009; animated) [Dr. Satan]: Run over by several motorcycles and cars in quick succession. (Played for comic effect.) (Thanks to Tommy)

The Last Station (2009) [Vladimir Chertkov]: Dies (off-screen) several years after the final scene; his death is mentioned in the on-screen text at the end of the film. (Thanks to Tommy)

Ironclad (2011) [King John]: Dies of dysentery (off-screen) while retreating; his death is revealed in the closing narration.

John Dies at the End (2012) [Arnie Blondestone]: Decapitated (off-screen) prior to the start of the film; he appears as a hallucination to Chase Williamson (assuming the form of what Chase thought he looked like) and his death is revealed when his real body (a special-effects dummy) is found in the trunk of his car. He later "dies" again when Chase stops imagining he's real, causing him to disappear.
Parkland (2013) [Abraham Zapruder]: Dies (off-screen) in 1970. His death is mentioned on the on-screen text at the end of the film, along with a photo of the real Abraham Zapruder.
Love & Mercy (2014) [Dr. Eugene Landy]:
Straight Outta Compton (2015)
Ratchet & Clank (2016; animated) [Chairman Drek]: Killed in an explosion by Armin Shimerman.

Morgan (2016) [Dr. Alan Shapiro]: Bitten in the throat by Anya Taylor-Joy as Kate Mara, Michael Yare and Chris Sullivan looks in horror. He dies from bleeding to death.
I Think We're Alone Now (2018) [Patrick]: Shot in the chest by Elle Fanning, while Peter Dinklage and Charlotte Gainsbourg look on.
The Catcher Was a Spy (2018) [Samuel Goudsmit]:
Gunpowder Milkshake (2020)

John Adams: Peacefield (2008) [John Adams]: Dies of old age/natural causes, with his grandson (Samuel Barnett) by his bedside. (Thanks to Stephen)