Frog

Frogs are recurring animals in The Legend of Zelda series. Most are not enemies, but either help or are helped by Link; for the most part, these amphibians are often encountered singing as part of a choir.

A Link to the Past
In A Link to the Past, the missing Dwarven Swordsmith can be found in the Dark World transformed in a frog-like creature due to the Dark World's magic.

Link's Awakening
In Link's Awakening, there is a frog choir lead by Mamu that teaches Link the Frog's Song of Soul after paying a large sum of Rupees. There is also a frog troupe inside Richard's Villa, as a reference to the game Richard originated from, Kaeru no Tame ni Kane wa Naru ('For Frogs the Bell Tolls').

Ocarina of Time and Majora's Mask
These animals are also included to great effect in Ocarina of Time and Majora's Mask as sidequest characters that must be befriended in order to earn both rupees and a Piece of Heart. In the same vein, five of these simple yet curiously useful creatures form the singing group called the Five Fabulous Frogs in the Zora's River in Ocarina of Time, and yet another five form the Don Gero's Frog Choir in the mountains of Termina, in Majora's Mask, as parallels.

Twilight Princess
In Twilight Princess, there are normal-looking frogs in Ordon Village that Link can talk to while in wolf form, however, these do not group together to form a choir, they simply exist as they would in reality.

Phantom Hourglass
In Phantom Hourglass, six Golden Frogs are placed in several locations throughout the World of the Ocean King. If Link hit them with a shot from the cannon, they will show him a symbol that can be drawn onto the Cyclone Slate to warp via cyclone to the location the symbol was learned.