Warcraft II: Tides of Darkness
December 09, 1995
In Warcraft II on the Temple of the Damned, a symbol looking like the Triforce can be seen on one of its boulders.
Note that this can't be proved to be an actual refernce, rather than a symbol that happens to look like the Triforce.
Warcraft III: Reign of Chaos
July 3, 2002
As a recurring joke in the series, if the player clicks on the same unit many times, it will eventually get angry and sometimes say jokes.
In Warcraft III after clicking many times on a "Druid of the Claw" a tinny music will eventually play and he will say "Can't ... stop ... dancing!" This is believed by some to reference Darunia in Ocarina of Time, who can't help but dance to Saria's Song, but once again there is not enough proof for this to be an actual reference, since the quote "Can't stop dancing" was used in many other works, totally unrelated to Ocarina of Time.
World of Warcraft Patch 1.11.1
June 28, 2006
With this patch many references to the Zelda series were added to the game. First, a Kodo named Dadanga can be found at Marshal's Refuge in the contested zone of Un'Goro Crater. Its name is based on Dodongo, a recurring enemy from the Zelda series, and its owner, an Orc called Petra Grossen even references the quote from The Legend of Zelda, "Dodongo dislikes smoke", when she states "If you have any lit torches or any open sources of flame, I'd like to ask you to keep them stashed if you could. Dadanga dislikes smoke." Dadanga also offers a quest called "Dadanga is Hungry", but that doesn't seem to reference the Zelda series. This quest is notable for being the only way in the game to obtain the recipe for the Elixir of Brute Force.
Additionally a chain of quests was added with the patch, the first quest being called "It's a Secret to Everybody", which itself is a quote of the Friendly Moblin from The Legend of Zelda. It starts in Un'Goro crater, after finding a wrecked raft, possibly referencing the beginning of Link's Awakening or the raft item from The Legend of Zelda, and the objective is to find the raft's owner. To do so the player first has to find a bag nearby the raft, containing a Curled Map Parchment, a Large Compass, and a Lion-headed Key, referencing the Compass, Map and Magical Key from The Legend of Zelda (notably, however, since these items reuse images from other items in the game, the Lion-headed key is not shaped like a lion in its image). The bag also contains a Faded Photograph of a pair of gnomes looking similar to Zelda and Link, standing in front of a ruined castle. The items belong to the male gnome, that can be found at Marshal's Refuge and is revealed to be named Linken, referencing Link. His appearance is based specifically on the original The Legend of Zelda, since he's short and has brown sleeves, however the white pants were first featured in Ocarina of Time. Linken gives the player his training sword to be brought to Donova Snowden in Winterspring, so that she upgrades it, and she does so simply by throwing it into the water, referencing how the Grat Fairy would upgrade Link's sword and other items in A Link to the Past.
Donova Snowden gives the player another quest called "The Videre Elixir", that consists in asking a gnome called Gregan Brewspewer the titular elixir. He will first ask the player to find the ingredients for it in a nursery guarded by a Gnoll called Miblon Snarltooth. This Gnoll's name is an anagram of Moblin, a common enemy from the Zelda series, and will say "Grumble grumble" when spoken to, quoting the Firendly Goriya from The Legend of Zelda. To distract him the player must purchase a Bait item, referencing the Food item from The Legend of Zelda, that was a bait used to distract enemies. Gregan also says "Buy something, will ya?" quoting the Old Men from The Legend of Zelda.
Donova will then give the player the quest "Meet at the Grave", referencing the quote from The Legend of Zelda, "Meet the Old Man at the grave". She will give the player Linken's Tempered Sword and instruction to reach the graveyard outside Gadgetzan in Tanaris and drink the Videre Elixir, making it possible for the player to meet a ghost called Gaeriyan.
In the quest "A Grave Situation", Gaeriyan will tell the player to push a specific gravestone in the Graveyard, referencing how the Magic Sword is found in The Legend of Zelda. Pushing the gravestone will upgrade the sword to Linken's Superior Sword, starting the "Linken's Sword" quest, that consists in bringing the sword back at him.
Linken then gives the quest "A Gnome's Assistance", that consists in finding the gnome J.D. Collie to help him get his memory back. She then gives the player the quest "Linken's Memory", that consists in finding the Night Elf Eridan Bluewind, and she gives the player the quest "Silver Heart", asking to Collect 11 Silvery Claws and 1 Irontree Heart. None of these seem to reference the Zelda series.
She will then give the player the quest "Aquementas", consisting in using the Book of Aquor to summon the titular water elemental, and turn the previously collected items into the Silver Totem of Aquementas. Aquamentas' name is based on the first boss of The Legend of Zelda, Aquamentus. Also, to find the proper spot to summon it, Eridan says "The eastmost peninsula is the secret..." referencing another quote from The Legend of Zelda. The quest is completed by taking the totem to J.D. Collie.
She gives the player the quest "Linken's Adventure", consisting in taking the Silver Totem of Aquementas to Linken. This quest's name is likely based on Zelda II: The Adventure of Link.
Linken will then give the player the last quest in the chain, "It's Dangerous to Go Alone", referencing the message from The Legend of Zelda spoken by the Old Man that gives Link the Wooden Sword, "It's dangerous to go alone! Take this." Linken even mentions this while describing the mission, saying "You will want to bring others with you—it's dangerous to go alone. Take this as my advice." The quest consists in slaying the fire elemental Blazerunner and taking the Golden Flame it was guarding back to Linken, but to do so the player must first use the Silver Totem to remove its magical protective aura, referencing how in many Zelda games the end boss Ganon must be hit with the Silver Arrows before being able to defeat him. The Golden Flame is shaped like a triangle (it actually uses the image of a triangular shield), and Linken even said "it is dangerous in the hands of one with an evil heart", referencing the description of the Triforce given in most games. After bringing the artifact to Linken, he will give the player Linken's Boomerang, based on the Boomerang from the Zelda series, and one of two possible rewards, by saying "Take any one you want!" again referencing a quote from The Legend of Zelda. The offered items are the Spirit of Aquementas and Linken's Sword of Mastery, this one referencing the Master Sword from the Zelda series. He also
(Note that all these exclusive items use the same images as other items from the game)
With Patch 4.0.3a, to make room for new quests that would be introduced in the Cataclysm expansion, This chain of quests, its exclusive objects, Linken, as well as Dadanga and its quest were removed. Dadanga was replaced by Dadanga's Grave, that also starts the quest "Here Lies Dadanga", but that doesn't seem to reference the Zelda series.
World of Warcraft Patch 4.2.0
June 28, 2011
With this patch Linken resourfaced on Mount Hyjal, aiding in the fight against Ragnaros' forces in the quest "The Protectors of Hyjal". In this occasion he's seen riding a brown horse that might be based on Epona from Ocarina of Time and some later games. Also his quotes include "Excuuuuse me, princess!" and "Oh, boy! I'm so hungry, I could eat a fire elemental!" based respectively on Link's catchprhase from the Zelda animated series, and on his first line from the introduction of Zelda: The Wand of Gamelon, that was "Oh, boy! I'm so hungry, I could eat an Octorock!"
The creators of Warcraft games didn't hold any right over Nintendo's Zelda, but they only included subtle references to the series.