I've jotted down as many as I could think of, see how many shows can you think of in each category.
Stupid Show, Serious Ending
A show that was really goofy for almost every single episode, or tried to be serious, and failed, tries to make shit get really dramatic in the final episode, leaving the viewer either teary-eyed or with a WTF sort of feeling.
Just Stopping at a Random Point
Stopping at a very obscure point in the story. Tends to make the show seem like it's going to get a sequel. Usually a sequel is never made, leaving fans dissatisfied with what they have seen.
Stopping at a Somewhat Conclusive PointStopping at a point in the story where it seems like the ending. Satisfies both anime-only viewers and people familiar with the source material on most occasions.
You Choose the Ending
Either displaying various alternative endings to the viewer, or leaving the protagonist in a position to choose their fate, not letting the viewer know what their choice was. Usually happens in anime adaptations for games. Feels a huge cop-out every single time.
Something completely unexpected happens in the last few minutes of the episode, leaving you with a feeling of "Wait, what?"
The Very "Comedy" Ending
Usually happens in, you guessed it, comedy series. Constant remarks about it being the last episode are made, and nothing really significant happens.
The Surprise SequelYou're presented with a conclusive ending, and in the very last second of the program there's the announcement for a second season or a movie. SURPRISE!!!
The Not-So Shocking RevelationSomething that seemed completely obvious throughout the entire series is revealed in the last episode.
I Know You're Out There SomewhereSomeone significant possibly dies in the episode, but there is no real proof of their death. Their friends are extremely confident that this person is alive, and continue on with their daily lives, or sometimes go searching for them.
The HaremMain character hasn't picked the girl/guy in their harem they want. No problem! He/She can have ALL of them.
Walking AwayAfter the final conflict ends, protagonist epicly walks of to wherever, sometimes with companions.
Problem Not Solved
The biggest problem in the series is not solved, the characters can't deal with it, and decide to either live with it, or hope someone else can fix it.
The Ridiculously Happy EndingUsually in action, fantasy, magic, and sci-fi series. Every single possible issue is solved with no deaths and little to no injuries. Even the stuff that seemed completely and utterly hopeless was solved in a manner that harms NO ONE (except the antagonist, on some occasions). YAY!
Anime-Original EndingsAdding in a conflict that does not take place in the original story. There are various types, most tend to leave fans of the source material with something else to bitch about.
So-and-So is leaving/dying but at the very last minute, they return?!?!?
The entire episode is dedicated to everyone feeling emo about a significant character having to leave or dying, but at the very last minute, they show up like "heyy, I'm baackk!" And everyone's all happy and sunshine and rainbows. Another cop-out.
The "Final" Battle
You think you're watching the final conflict in the story, but really, that was just some bullshit the anime writers put in to make it seem like a proper ending.
"Welcome to ______"
If the show's about a certain group or club, the final episode introduces one or two new characters in the very last few minutes, or just show the usual characters sitting in or standing in front of wherever the group gathers, welcoming the new members.
Almost All the Significant Characters of the Story Gather in One Spot for Absolutely no Reason
Usually takes place at the very end of the final episode. Not too sure what the point of such a scene is, but I've seen this happen on multiple occasions. Honestly, it's extremely stupid.
Other Elements of Anime Endings that are Typically used:
- Playing the first opening theme of the series (instrumental, orchestral, or the original version) during the last bits of the episode
- Cameos of characters from the source material who did not make any earlier appearances in the anime
- A kiss scene
- Someone dies, and everyone is sad about it for five minutes, then they don't give a f**k anymore
If you can think of another anime ending that I haven't named, feel free to tell me.