Peaceful in Death

Only the dead have seen the end of war.

—George Santayana (often misattributed to Plato)

A dead character has a peaceful expression. Sometimes noble and dignified as well.

May follow Go Out with a Smile, Obi-Wan Moment, and Big Sleep, but may also have died in visible misery and pain, with Dies Wide Open. May be part of This Was His True Form, and result from Dying as Yourself.

The mundane (or Maybe Magic, Maybe Mundane) equivalent of Died Happily Ever After.

Real Life embalmers are paid good money to achieve this effect. The muscles in the face tend to constrict slightly during the ebalming process, often resulting in the appearance of a faint smile on the corpse.

As a Death Trope, Spoilers ahead may be unmarked. Beware.

Examples of Peaceful in Death include:

Anime and Manga

How the eponymous boxing legend dies in Ashita no Joe. He seems to be peaceful, knowing he has won the match despite it costing his life.
- That scene has inspired countless homage, from the tearjerkingly straight such as Kamina to the ones played for laughs such as Animate Tenchou.
Grimmer in Monster, upon finally feeling emotion.
Buccanneer, King Bradley, and Hohenheim all go out like this as Fullmetal Alchemist finally comes to a close. All three are smiling and lying on the ground very calmly and serenely.
One Piece seems to say that anyone with the Will of D tend to go out like this. Look at Ace andhis parents all smiling and at peace.
Babel from Saint Seiya.
Togame in Katanagatari after her Dying Declaration of Love.
In Umineko no Naku Koro ni, Maria is found this way in the fourth arc. Battler notes that the murderer apparently went out of their way to make her look that way, and it actually looks pretty squicky, since she's lying so peacefully in the lap of her mother, whose face was half-blown off, surrounded by adults whose faces were half-blown off.
In Naruto, Chiyo's brother Ebizo laments that she's not pretending to be dead, but notes how peaceful she looks.

Comics

Although we don't see his face, the first Dove (of the superhero duo Hawk And Dove) is at peace in death, to the point of being one of the few dead characters that were immune to being raised as a zombie by the dark-emotion-powered Black Rings in Blackest Night. Considering he was an avatar of peace, this is appropriate.

Films -- Live-Action

Parodied in Scary Movie 3: "My sweet sweet Brenda---She looks so peaceful..." (cut to Brenda with a horrified expression and hands like claws)
When the Badass Vampire Lord David finaly died in The Lost Boys he mysteriously lost his wicked stubble and looked about ten years younger - A Lost Boy if you will. A lot of people has said that the perfect ending of that movie would be a shot of a "Missing Child"-Poster from 1950 with Innocent David on it.
In American Beauty, the peaceful face of Lester in his moment of death is not only the result of his growth through the entire film, it also pretty much encapsulates the theme (the spiritual joy of finding "beauty" in the seemingly banal or even supposedly ugly products of everyday life).
In The Storm Riders, a martial artist uses magic to allow his dead girlfriend to rest peacefully.

Literature

In James Swallow's Warhammer 40,000 novel Deus Sanguinius, when Rafen goes to pay his respects to his dead mentor (and engage in Talking to the Dead), he is struck by how peaceful he looks, unlike the contortion racking him, as he died Fighting From the Inside to warn Rafen.
In the appendices of JRR Tolkien's The Lord of the Rings, it is said that Aragorn's face upon succumbing to death struck all who saw it as peaceful and noble.
In Robert A. Heinlein's The Roads Must Roll, a man is murdered while trying to negiotiate with the striking workers. The main character is struck by the nobility of his expression, seeing him dead.
Discussed Trope in The Outsiders. The kid who dies "Didn't look peaceful. He just looked dead."
In Anne of the Island, Ruby Gillis finally admits to Anne that she is dying and confesses it terrifies: all she will lose in life, and she has not readied herself for Heaven. But after she dies that night, her face shows that Death brought a wisdom that years of experience might have earned her.
In A Song of Ice and Fire, Tywin Lannister appears to have a faint smile while lying in state, and his children note how inappropriate the expression seems on him.
- Well he did die while on the privy maybe it was just really THAT good.
Dracula, surprisingly enough for all those who first knew him through Popcultural Osmosis.
In All Quiet on the Western Front, when Paul is killed, his facial expression is described as "calm, as though almost glad the end had come."
In Aleksandr Solzhenitsyn's The First Circle, a character freezes to death in a cell, and when they took him out, he was smiling. (The readers know that he had come to the conclusion that he had done the right thing.)
In Eragon, Brom gets encased in a diamond tomb after he dies. Eragon comments that he looks so peaceful.
In Teresa Frohock's Miserere an Autumn Tale, Rachael notes, on Catarina's death that the woman doesn't look peaceful.
In Angie Sage's Physik, after Alice takes a bullet for Jenna.

Theatre

In Street Scene, Rose says of her mother: "She looks so quiet and natural. You'd think she was asleep."

Videogame

The Boss in Metal Gear Solid 3: Snake Eater. Hell, she was at peace with the idea that Snake would kill her for weeks and even comments that their fight together should be the best ten minutes of their lives.

Western Animation

Parodied in Kung Fu Panda. Shifu almost slips into this trope, and he looks like he has died with a serene expression on his face, and then he opens his eyes, saying that he's not dead, he's at peace.