Easter eggs!!!

The two most memorable for me are cameos in Super Mario RPG, the fantastic SNES RPG which was a joint project of Nintendo and Squaresoft (now known as Square-Enix), of which all of the Paper Mario games are spiritual successors. During one part of the story, if you go to the Inn at Rose Town , you'll see Link from Zelda asleep in a bed upstairs. At another certain part, you can find Samus from Metroid inside of Pricess Toadstool's castle in the Mushroom Kingdom.

 

I have a few memorable ones that I will mention here.

Skyrim: Is full of Easter eggs. There is a character that will say something along the lines of "It's a secret to everybody" which is a reference to the character from the original Zelda game. Skyrim also has many other references, such as; Starwars, Bioshock, 300, and other games and movies. There is also a character named Aamus Sron, which if you flip the two first letters around it says "Samus Aron"

Zelda Ocarina of Time: in Zelda's courtyard if you go to one of the windows (i think it's the one on the right) There will be pictures of Mario, Luigi, Peach, and Yoshi hanging on the wall inside the castle.

Boarderlands: Has so many Easter eggs in it, I don't know where to start. But they do seem to enjoy referencing songs.

Pokémon X & Y; Referenced Harmoknight. I love that game so much <3

That's all i can think of at the moment.