After saving Simba from the hyenas and scolding him for endangering both himself and Nala, Mufasa and Simba have a heartwarming father/son moment:
Simba: Dad? We're pals, right? Mufasa: Right. Simba: And we'll always be together, right? Mufasa: Simba, let me tell you something my father told me. Look at the stars. The great kings of the past look down on us from those stars. Simba: Really? Mufasa: Yes. So whenever you feel alone, just remember that those kings will always be there to guide you... and so will I.
What makes it even better is that Mufasa diverts Simba's question a little, whilst answering it at the same time. He's effectively telling Simba that he won't always be around, but that he will always be with him, at least in a sense.
Simba expected to be getting the stern disciplinary lecture that no kid wants, and he does at first...but then it turns into a father/son moment from there.
Mufasa: Being brave doesn't mean you go looking for trouble. Simba: But you're not scared of anything. Mufasa: I was today. I thought I might lose you.
The stage version subtly emphasises this; before his talk with Simba, Mufasa removes his lion mask from his head and places it and his two machetes on the stage. Essentially removing his royal regalia so he could speak to Simba, not as king to prince, but as father to son.
James Earl Jones's performance during the scene, hearing his deep dignified voice when Mufasa laughs while rough housing with Simba somehow makes the whole scene even more adorable.
Plenty of obvious examples in this movie, from some of Mufasa's talks with Simba to arguably the sappy "Can You Feel The Love Tonight" song, but especially worthy of mention is when Timon says "Well Simba, if it's that important to you, we're with you to the end!", because Simba's his friend and they're in this together no matter what.
And the look Simba gives him afterwards...holy cow you almost break down in tears every time you see it, but especially in this instance, since Timon and Pumbaa didn't have to do what they did.
The end, with the "Circle of Life" reprise playing as Rafiki presents Simba and Nala's new baby to the world, just as he did with Simba himself at the beginning of the movie.
Simba as as a newborn cub in the beginning is just adorable to some.
The audio commentary even mentions that the moment where baby Simba turns around always got an "Awwwww..." whenever they saw the film with an audience.
That moment when Simba feels most alone, then suddenly Rafiki appears, chanting his rhyme, to help him.
Which has the payoff in what he shows Simba in the jungle pool. Here we have Simba, once he finally realizes the "creepy little monkey" isn't completely yanking his chain, but actually did know Mufasa. He tries to break the news of his death to him gently, only to be told, "He's alive, and I'll show him to you!" Despite his misgivings, he follows Rafiki (one of the storybook novelizations even had him think in his thoughts that he actually would get to meet his father again—he's that lonely, desperate, and guilt-stricken he naively believes his father is literally still alive!) until they reach the pool. There he realizes its not true and says, "That's not my father, that's just my reflection," to which Rafiki says, "No...look harder, to which Simba's reflection changes to Mufasa.
Simba: Yeah, but it still hurts! Rafiki: Ah yes, the past can hurt. But the way I see it, you can either run from it, or learn from it.
Rafiki when he discovers Simba's alive. He starts laughing hysterically as he takes red paint and paints a mane on the picture of Simba he smudged when he thought he was dead. Accompanied by awesome music.
Crossed with Crowning Moment of Awesome, Simba ascending Pride Rock in the rain and roaring - how proud everyone is of him, seeing him nuzzle his mother and Nala, and Zazu bowing to him.
Fun fact: if you look closely when Zazu bows, you can see his beak moving but no sound. This is because the script initially called for him to say "Your majesty" when Simba walked by, but it was scrapped because they decided it would be more poignant if there was no dialogue. ( Although Rafiki has a line and Mufasas ghost says "remember") This is kept in the theatre production.
The brief smile of confidence on Simba's face just before his roar when he hears his father's voice in the clouds is just the icing on top.
The entirety of "Can You Feel the Love Tonight" certainly qualifies to some but special mention goes to Simba and Nala's reunion. These two are in the middle of an epic beatdown, and all it takes is for Nala to pin Simba for him to remember her. Even though he's been gone from the Pride Lands for years, he never forgot his best friend. Then it goes up to eleven when Nala realizes that the lion she's been fighting is her friend she thought was dead and gone and the two react like...well like cubs.
This leads to a funny moment when Timon's reaction is a perplexed Jaw Drop.
Later on, Simba finally pins Nala. It was never even intentional, but they just smile at each other like they know what it means.
The fact that Simba takes on Nala in order to save Pumbaa, despite likely has not having any real combat experience since he was a cub. Naturally, he is beaten, but he did save his best friend.
The end of "Can You Feel the Love Tonight" in the theatre production gets changed up from Timon and Pumbaa's sad thoughts to these final lines between Nala and Simba:
Nala:And if he feels the love tonight In the way I do... Simba:It's enough for this restless wanderer Simba and Nala:Just to be with you.
When Scar and Sarabi are arguing, Sarabi yells at Scar for not being half the king Mufasa was. Scar hits her and knocks her down. This enrages Simba but he goes over to nuzzle his mother. Doubles as an Awesome Moment since Scar is scared for his life.
At the end, as Rafiki beckons Simba towards Pride Rock. He bows to him and Simba grabs him in a tight hug, effectively thanking him for all that he's done for him.
This also mirrors Mufasa's hug of Rafiki right before the presentation of Simba at the beginning. They even both hug him with the same paw.
When Sarabi sees a grown up Simba for the first time, it's subverted as it's amid a moment of drama and sadness, and Scar quickly interupts.
Combination this and Crowning Moment of Awesome when Simba and Nala are being chased by the hyenas in the Elephant Graveyard. When Nala falls behind, Simba immediately turns around and rushes to her defense, scratching the face of the much larger hyena and giving Nala time to climb away. And when they are cornered, he places himself between Nala and the hyenas and tries to roar at them in a desperate attempt to intimidate them. He's just a kid against full grown predators(who, admittedly, except for perhaps Ed, are incompetant), but he intends to go down fighting them to defend his friend.
Another scene in the Elephant Graveyard that has both this and Crowning Moment of Awesome except this time with Zazu. Simba and Nala had been nothing but a thorn in his side for the entire day and when he had finally caught up to them after they ditched him, he is understandably furious and irritated at the disrespect and disobedience of his charges. But the moment the hyenas reveal themselves, he immediately raises his wings and shields the cubs. He is on the ground the entire exchange and makes no move to fly away until the hyenas are thoroughly distracted and the children are running.
When Shenzi stops them from leaving and hints at "having them for dinner", there's a quick blink and you'll miss it moment where Zazu, who is only half the height of the cubs, places himself in front of the children with his wings outstretched and closes his eyes, fully prepared to die for his prince. Zazu is truly selfless, heroic, and would do everything in his power to serve and protect the royal family.
When this clearly fails, Simba, despite all of the crap he has put Zazu through, attempts to defend him.
Crossed with Tear Jerker, but in the gorge scene, Simba cries out for Zazu to help him. Zazu reassures him that his father is coming and tells him to hold on. Simba has caused Zazu plenty of irritation in the past, but Rowan Atkinson's excellent voice acting definitely gives the impression that right now Zazu would give anything to be able to pull Simba out of harm's way.
Two out-of-film examples, proving just how much the film touched audiences around the world:
In a program which aired in the UK back in 2005, detailing the top 100 family movies of all time (The Lion King was number 6), one of the producers revealed that they received a letter from a young boy who had been devastated at the loss of his father. Unsure what else to do, his mother took him to see the film as a way of cheering him up, completely unaware of what happened in it... But rather than make things worse, the film actually helped him come to terms with what happened.
Another similar story was detailed in the special features of the 2-Disc Special Edition, in which a man lost his wife but had no idea how to tell his young child, who was too young to understand what death was. So he showed his child the film, and then explained that while Mummy was gone, Mummy was always watching over them. The woman telling the story was nearly in tears by the end.
"...and when your films do that...it makes it all worth while."
While not despicable enough to be the Tear Jerker it is in real life when a child loses consciousness, the part where Simba has lost consciousness from heat and starvation in the desert, with vultures flying around him, is an emotional bit and does make some people want to help the cub.
The stage show
At one point Mufasa is bemoaning Simba's immaturity and unwillingness to behave. Zazu reassures his king by telling him he actually reminds him of another cub he used to know who turned out just fine, clearly referencing Mufasa himself. It's a reference sure to induce "Awwwww"s all by itself (Cub Mufasa!), it's Zazu doing his job by showing his concern for his king and advising him truly, and it shows for all his irritation and annoyance with Simba, he must believe in him since he's already been through this before with his father, and just compared them favorably. (Not to mention if he's been through it before but is still sticking around, he knows the results will be worth it and it doesn't bother him quite as much as he lets on.)