Hammer
Throughout the Zelda series, multiple types of hammers appear in each game. These hammers vary in size, name, and design, but all serve the same purpose. SMASHING STUFF TO PIECES! Every variation of a hammer has its limitations, and thus must be used a accordingly. Link, stop smashing stuff to pieces!
Adventure of Link
In Adventure of Link, Link finds a hammer that is used to smash boulders and forests. Link receives the hammer in a hole deep in Death Mountain. This was the first appearance for the hammer, and really set the tone for the following games.
A Link To The Past
In the classic SNES game, a hammer makes an appearance. This time it's called The Magic Hammer. Funny name considering it doesn't cost any magic power to use. This weapon is used to lower stakes to advance further in the game, or to solve puzzles. It is found at the first dungeon in the Dark World, Dark Palace.
Ocarina of Time
In the third appearance of a hammer, Ocarina of Time showcases the Megaton Hammer. This hammer is very usefull against Torch Slugs, flipping them over to their weak point. It is also used on Rusty Switches that cannot be pressed otherwise. It can also smash up red boulders that bombs cannot, most of these boulders coming from Death Mountain. It is the dungeon item of The Forest Temple, the first Adult temple.
Wind Waker
In Link's first adventure on the gamecube, there is a tough hammer known as the Skull Hammer. It is found at the Forsaken Fortress the second tiem around. In can be used to smash up spikey or wooden pegs that may be blocking your way.
Phantom Hourglass
In the first Zelda DS, Link gets an item known as a hammer. It is useful against enemies that you were unable to defeat without it. It is found on the 3rd Floor of Mutoh's Temple, and is needed to defeat the boss, Eox.