The Avengers: Earth's Mightiest Heroes/Tear Jerker

Season 1
"Bucky: "Sorry, Cap!"
 * After Black Widow frames Hawkeye of betraying SHIELD, she softly admits that she'll miss working alongside him. During the first viewing of this episode, it feels hard to tell whether or not she means it, so it doesn't get especially depressing until 18 episodes later. Widow and Hawkeye agree there that any of her other possible actions could have ruined Nick Fury's plans.
 * Bucky, kicking Captain America off the missile he is trapped on rather than letting Cap risk his life trying to save him.

Captain America: "Stow that talk, we'll make it!"

Bucky: "No, I mean sorry, but the world needs Captain America more than Bucky!"

(Bucky kicks Cap off of the missile)

Captain America: "No! NO! BUCKY!"

(missile explodes)"

""I should have never woken up. I'm a solider, not some future man. I can't imagine a world that's changed so much still needs... Captain America.""
 * After the Hulk snaps out of the Enchantress' spell, he discovers it lifted right before he could flatten Wasp, the first Avenger who showed kindness to him. He gently places her on the ground, then considers the possibility that he really is a Complete Monster.
 * Captain America's period of doubting his relevance in the modern day feels pretty wrenching.

"Wasp: "Should we move his hammer? Hulk maybe--"
 * Tony reflecting at the end of "Everything is Wonderful" about how his plans to save Simon's company and promote his impressive projects fell apart, and his actions instead resulted in Simon apparently disappearing.
 * Black Panther recalls to Captain America about how he failed his father during the duel with Man-Ape, and tells Cap that since he must also bear memories of failing to save a loved one, he should understand why Panther must defeat Man-Ape by himself.
 * "459" has Jan accuse Hank of shunning her in favor of scientific experiments and extraterrestrial encounters. While she chews him out on this, the Kree sentry robot fires some missiles at her. Hank defends her from them, but gets knocked out in the process. Right before he goes unconscious, he tries to reassure Jan that he loves her, but collapses before he can finish.
 * From the same episode, Jan visiting an unconscious Hank in the hospital and apologizing about her attention-hungry behavior.
 * Black Widow apologizing to Hawkeye about all the suffering he went through after she framed him.
 * The team mourning Thor's loss in "The Ultron Imperative" is driven home by this exchange:

Hulk: "Can't move it. Can't even lift it."

Wasp: "Why not?"

Hulk: "Because... I'm not Thor.""


 * Hank deciding to leave the team after the Ultron incident.
 * Giant-Man finding the unconscious Wasp in Jotunheim, and expressing regret that he didn't say "I love you" soon enough.
 * Cap looking over his broken shield at the end of the season finale.

Season 2
"Iron Man: "I started this team because I needed people I could count on, and now I can't. The Avengers are over as far as I'm concerned.""
 * Hank is noticeably absent from the first four episodes, having quit the Avengers to try and work through some of his issues.
 * There's something incredibly sad about how Mar-vell tries to have Ms. Marvel understand why Earth had to submit to the power of the Kree Empire. Here's a man who wanted to protect earth at any cost, and now the resistance of its heroes might lead to the destruction of a planet he's fond of. He just seems so torn up.
 * "I'm not [Ant-Man], Jan. I haven't been since Ultron, and honestly, maybe even before that."
 * Later, Hank tries to call Jan for help in retrieving the stolen Ant-Man suit, but she refuses to talk to him. She's just as heartbroken at his leaving, and already spent the first part of the episode begging him to come back.
 * In the same episode, it's very sad to watch Hank's Heroic BSOD. Notably, that his voice is much lower than before, indicating a strong depression in the character.
 * Not to mention Scott Lang's entire story, a single father trying to do right by his daughter and life just keeps throwing him curveballs.
 * The Kree separating Michael Korvac from his girlfriend for . By the time he finally makes it back to Earth,.
 * Or, given the final shot of the episode, It's pretty heartwrenching no matter how you look at it.
 * Plus, the episode ends with a dedication to deceased animation director Boyd Kirkland.
 * Paranoia about Skrulls causes the Avengers to lose trust in each other. of them,  even quit the team.

"Ms. Marvel: "This was supposed to be my welcome party.""
 * Later:

"Thor: The Skrulls turned you against each other. Broken bones, destroyed buildings, these things are easily repaired. But broken friendships, broken trust, wounds such as these take much longer to heal."
 * The next scene of Tony shows him alone in his office, staring at his mask as it sits on the desk.
 * The tragic backstory of Beta Ray Bill. Basically, Surtur's awakening led to their genocide in what had previously been a relatively peaceful realm (aside from Surtur trapped as a Sealed Evil in a Can, which they didn't know about), with the survivors then pursued for almost as long as Beta Ray Bill could remember.
 * As bitchy as Amora may have been, one can feel nothing but pity for her when she begs Bill and Thor to help her... by giving her a Mercy Kill. Unfortunately, before they can even try to help her, Surtur takes her back to his hell dimension.
 * After the Avengers and Nick Fury discuss everyone's success in preventing the Skrulls from taking over the world, Captain America sadly leaves the room.


 * For context, the fake Skrull Cap had just (prior to the Avengers' epic victory over the invading Skrull forces) convinced the world to surrender. Of course, this being the Marvel Universe, one can assume that they're not going to take too kindly to Captain America (or, at least, some creep impersonating him) apparently selling out humanity. And of course, this on top of Skrull!Cap's other crimes while impersonating the real Cap, like attempting to turn the Avengers against one another and so on.
 * "Along Came a Spider" opens with
 * Blizzard's . Given how he actually acted as a reasonably nice guy in that episode and Took a Level in Badass, it's somewhat upsetting.
 * The ending of "Ultron Unlimited". Vision's very thought-provoking statement and the silent reactions of all the Avengers really hits home.
 * Before the robot Avengers captured Ms. Marvel and Thor, Iron Man told Ms. Marvel that she doesn't do a good enough job at acting like an Avenger, and Thor that he should have never come to Earth. Both of them initially saw this as Tony Stark himself chastising all the hard work and contributions they've made for the team.
 * Where to begin with "Yellowjacket"? The Sanity Slippage of Hank Pym, ...