Darker And Edgier / The Legend of Zelda

• While Zelda II: The Adventure of Link lacks the details to properly show it, the game is a bit darker compared to The Legend of Zelda. The reason there were no towns or settlements in the first game was due to everyone evacuating and moving up north to avoid Ganon's forces. Despite the move, Old Kasuto is completely abandoned by its people once Ganon's minions found them; going there has no NPCs (save for a hidden one that teaches you a spell) and there's invisible enemies everywhere that you cannot see unless you picked up the Cross. Thankfully, Old Kasuto's residents moved to a hidden area in the woods that you can get to once you reveal the location. On top of this, one of the town's children was kidnapped by one of Ganon's minions, which you do get to rescue. There's also the fact that all of Ganon's minions are actively hunting down Link where it's not just for revenge, but for Link's blood specifically, which is needed to revive Ganon. Get a Game Over and, if you’re in America, you see Ganon rise again as he laughs. If you’re in Japan, you might not see him, but you do hear him roar.
• A Link to the Past managed to be even darker than its NES predecessors, with the intro cutscene showing the king of Hyrule as a lifeless skeleton, and the tutorial level showcasing such things as Link's uncle dying in front of the young lad, countless knights falling victim to corruption and subsequently being killed by your hand, and you having to escort Princess Zelda through the castle sewers so she doesn't become a (albeit non-lethal) Human Sacrifice. That's just how the game starts; throughout the rest of the adventure, Link is a Hero with Bad Publicity, minor characters frequently die, and soon after you get the Master Sword, Zelda is successfully sacrificed and you have to traverse the Dark World, a corrupted Sacred Realm where many have ventured and never returned. Granted, it's all undone by the Triforce at the end, but that's quite the jump in intensity between console generations. And to top it all off, a Cerebus Retcon later down the line places this game as the first in an alternate timeline to Ocarina of Time, where that game's Link is killed by Ganon.
• Ocarina of Time is darker than the preceding games, dealing openly with more mature subjects such as war, devastation, and even death (it's more prominent during the future era, when Ganondorf successfully takes over Hyrule).
• Majora's Mask goes further than Ocarina of Time with its apocalyptic concept of the moon falling into the land of Termina in three days. The game completely subverts the Take Your Time approach present is most of the other games in the franchise, which helps give players a perpetual feeling of imminent dread. The tone is also comparatively bleaker, as many of the characters in the game are put through endless suffering and often border on the Despair Event Horizon. If you run out of time, you actually get to see the moon fall, where it explodes into a huge ball of fire that rolls across all of Termina, including Link himself who can't do anything to stop it as he too gets destroyed. As for the villain... Majora is not an Evil Overlord driven by human desires, but an Eldritch Abomination who is killing the world for reasons that are completely alien, making the Big Bad feel as much like an impending natural disaster as the moon looming overhead.
• Twilight Princess rivals Majora's Mask as the darkest entry in the franchise. While the tone is slightly less bleak, the story deals with more macabre themes. There's more complex Character Development among the main cast, there's general depictions of corruption, paranoia, and death, and the darker fantastical elements (literally and metaphorically) give the game a much more eerie atmosphere. Not to mention, most of the enemies in the game absolutely reek with Body Horror, which isn't helped by the game's more semi-realistic art style. In fact, these were the reasons why the game became the first and so far only installment in the Zelda franchise to receive a T-rating, as opposed to its usual E-rating.
• Spirit Tracks is this to Phantom Hourglass, which is reflected in that it's one of the only two Zelda games in the Toon Link style to not receive a regular E rating, but rather E10+ (the other game being the HD remake of Wind Waker). The antagonist is a twisted, corrupt politician who is actually a demon in disguise, and the story features one of the shortest, but creepiest plot points of Twilight Princess as framework for a huge chunk of the story: Princess Zelda's empty body being possessed by a male Sealed Evil in a Can.
• Skyward Sword is in the middle between the darker style of Twilight Princess and the lighter style of The Wind Waker, which is evident by both the visual style and the storyline. Played literally with the final boss' weapon: a black Master Sword with a Serrated Blade of Pain.
• Breath of the Wild has a light visual style that mixes the tones of Wind Waker and Twilight Princess. Its plot is also in a middle ground between the two games, with a lean towards TP level of darkness. Link has been in a coma for the last century and is presumed dead. Unlike him, most of his group of friends didn't make it out alive. In that period Hyrule has turned into a desolate wasteland full of monsters.