I'm going to add this because I am honestly ashamed I missed this detail.

Levi gives Petra's crest to Dieter and tells him it's Ivan's.

"He's alive, but filthy. Forget about it.." < Levi was talking to himself here. I found that cute.

 

"The human whose name is written in this note shall die."

 

...So Levi stomping the female titan and showing he is without a doubt the strongest solider of humanity (Mikasa ain't shit) Gilgamesh revealing EA in Fate Zero and Riders final charge.

 

MAJIN VEGETA'S SACRIFICE. Swear to God people, this scene is way too emotional, all the way from childhood.

Assorted others (Spoilers):

Death Note - L's death, Light's death

Code Geass - The ends of both seasons. 'I destroy worlds... I create worlds'

D.Gray-Man - Tyki Mikk 'killing' Allen

Fate/Zero - Motherfucking Rider against motherfucking EA, Kiritsugu being a ruthless bastard

Clannad - Emotional scene between Tomoya and Ushio in the grass

Gurren Lagann/DBZ - Where to begin?

Getbackers! - Akabane vs Ginji

FMA (not Brotherhood) - Maes Hughes' death

 

Code Geass - End to season 2.

Toradora - The scene where Taiga is giving out the chocolate.

Gurren Lagann - Kamina!!