1 Giygas Battle from Earthbound
2 Meat Circus from Psychonauts
3 Omega Flowey and Amalgamate boss battles from Undertale
4 Flint's reaction to Hinawa's (his wife) death in Mother 3
5 Ballos' fourth AKA "soul-bleeding face" form from Cave Story
6 Mario going to hell (The Underwhere) in Super Paper Mario
7 Crocomire's death in Super Metroid
8 Mario dying for real (most notably by drowning) in Super Mario 64
Expanded MASSIVELY upon in Mario Galaxy, but this did it first - xandermartin98
9 Link clutching his head and screaming in agony during his mask transformations in The Legend of Zelda: Majora's Mask
10 Lammy dying from cranial trauma and going to hell in the original Japanese version of Um Jammer Lammy
11 Peach Rejecting Mario's Proposal in Super Mario Odyssey
The saddest moment in a Mario super fan's life.
12 Tabuu Controlling Crazy Hand Like a Puppet Reminding People that It's the Same as an Autistic Person's Bullying Struggle - Super Smash Bros Brawl
13 Master Core in General - Super Smash Bros 4
It reminds me that my biggest fear is... myself :(
14 Pokewars - Pokémon Xy
15 Sephiroth Kills Aerith - Final Fantasy VII
16 Gruntilda's Fall to Her Doom with a Stone Crushing Her in the Process - Banjo-Kazooie
17 Alphys' Suicide Attempt - Undertale
18 Curly's Death - Cave Story
It's already on here.
19 Bowser Transforming Into Giga Bowser at the End of Adventure Mode - Super Smash Bros Melee
I'm not good enough of a player to unlock the battle.
20 The Intro, in Its Entirety - Banjo-Tooie
WHAT A DARK OPENING!
21 Gruntilda Killing Bottles and Destroying Banjo's House in a Single Strike - Banjo-Tooie
22 Aipom's "Death" - Detective Pikachu
Don't worry, it's just a TROLL. It's from a berry, not blood.
23 Master Hand's Death - Super Smash Bros. Brawl
24 Samus Becomes the Metroid Queen - Metroid Fusion
This is why I hate Metroid Fusion.
25 Samus's Backstory - Metroid: Other M
26 Zemus Resurrects as Zeromus and Kills Golbez, Fusoya and Cecil's Party - Final Fantasy IV
27 Sa-X'S Transformation - Metroid Fusion
28 Elder Princess Shroob's Transformation - Mario & Luigi: Partners in Time
29 Queen Metroid's Alternate Power Bomb Death - Another Metroid 2 Remake
30 Queen Slug-For-A-butt's Death - Earthworm Jim
31 Ballos' Backstory - Cave Story
32 Quote's Backstory - Cave Story
33 Genocide Run - Undertale