Death

Given the child-friendly nature of the series, one may not expect death to be a major concept in the brands history. However, mortality and death have been recurring concepts throughout the series, since the early days, typically ranging from from ambiguous deaths to the very few on-screen deaths.

Unlike most toyetic series, deaths in My Little Pony usually are not done for marketing reasons, or at least not overtly so (death of a character usually translates into a new, more favorable character or the chance for the dead character to return with a new form, and thus a new toy) but is often done for backstory or dramatic purposes. Most deaths in the series are implied only, but there have also been instances of characters exclaiming phrases that mentions words like death, dead, kill, etc. There have also been instances of villains threatening to murder others, but these are relatively rare.

My Little Pony cartoon
A humorous example appeared in "Would Be Dragonslayer", where Squire Alonzo claimed he wouldn't hurt Spike, he would slay him instead. Given his naive and kind of dimwitted personality, it's possible Alonzo didn't even know slaying meant killing.

Though never directly dealing with deaths, "Baby Its Cold Outside" involved King Charlatan nearly killing his son, Prince Edgar when his greed went to far, and feeling guilty as a result.

Being the infamously dark special that it was, "Rescue at Midnight Castle" has a few moments of potential death with one seen death. The three most noteworthy accounts involve Applejack, Spike and Tirek.
 * Around the middle of the first half, Scorpan only delivers three Ponies to Tirek, who demanded four. For his failure, Tirek threatens to cut Spike's head off.
 * Near the end of the first half, Applejack falls into a raging river after an accident on a rickety bridge. Being the selfless girl she was, Megan jumped into the river to save her and the two nearly drowned before being saved by the Seaponies.
 * Near the end of the second half, Tirek tries to enact the eternal night by unleashing the Rainbow of Darkness upon the world, but his darkness is countered by the light. In doing so, Tirek dies, causing all his dark country to cease to be.

My Little Pony Comic
In "Applejack's Amazing Adventure", she struck the Jewel Throne with such force that it cracked opened and opened a crack that went as far as the "ends of the earth", causing the Jewel Wizard to fall down it and presumably die.

My Little Pony Tales
In "The Slumber Party", Bazzle ended up causing the death of the boy Squire who still hunts Bazzle hundreds of years after his death as a ghost. In the same episode, Squire encountered the belongs of a long dead Knight.

Death was depicted many times in "Ponies in Paradise". The first time was when thought that the ponies of Tropical Island would cannibalize, another was was when  thought the ponies would hurl Bright Eyes into the Hungry Volcano, so it may devour her and stop erupting. Lastly, Bright Eyes nearly fell into the volcano itself, nearly killing her.

In "Whos' Responsible", Bright Eyes feared that the pollution of Big Pony River would "kill all the fishes".

Friendship is Magic cartoon
Although never explicitly stated, it's heavily implied that Applejack's parents have since passed away. This is evident by how they're always mentioned in passing, such as Applejack saying her mother "loved both sides of her family".

Friendship is Magic comic and spin-offs
In, a map is shown depicting two graveyards.

In, Chrysalis sacks an entire village of Kitten bunnies, causing them to die out. She kept he one known survivor and smashed it against a wall to scar the Cutie Mark Crusaders. Later in the issue, she claimed she couldn't stomach the thought of eating the Crusaders anymore, as the idea of them being inside her caused her great discomfort. Instead,she vowed to lether minions eat them instead.

In "The Fall of Sunset Shimmer", several books containing implied death contents were shown, such as the Haunting of Hill Horse, Condestoga Cannibalism, Infamous Cemeteries of Equestria, Soylent Green Recipes, etc.

Legends of Magic and Nightmare Knights
In an alternate dimension, Stygian proclaimed that Flash Magnus and Rockhoof both died, with Rockhoof having an accident in his towns volcano. He also claimed that he killed his universes Starswirl the Bearded Daybreaker later revealed that she and Stygian had killed Nightmare Moon after she rebelled against the Pony of Shadows.

Though never explicitly stated, Princess Eris's entire motivation is to destroy the world from the inside by causing the most destructive of chaos, which would undoubtedly cost at least some ponies their lives.

Suicide
The idea of suicide and self-harm is even rarer in the My Little Pony brand, but at least one instance of a potential suicide exists, albeit in a mythological context. In, after Queen Chrysalis had sacked Timbucktu and trapped all of its residents, the monarch of the land, King Orion was left in a near death state. Ashamed by his failure, Orion escaped the city and flew to deep into the sky until he eventually became "starlight".