Bongo Bongo

Phantom Shadow Beast: Bongo Bongo is the boss of the Shadow Temple, the seventh or eighth dungeon in The Legend of Zelda: Ocarina of Time.

Story
Bongo Bongo is a gargantuan invisible evil spirit that was sealed away in the well in Kakariko Village by Impa. However, when Ganondorf assumed power, Bongo Bongo eventually broke the seal placed on him and set Kakariko Village on fire. Link arrives just as Bongo Bongo escapes, but fails to stop it from traveling to the Shadow Temple. Link chases after him into the temple.

Battle
Bongo Bongo beats the drum, setting up a fast, softer beat with one hand but tapping much harder with the other one. The heavier drum beat would bounce Link up into the air. Bongo Bongo always stayed on the opposite side of the drum, as far away from Link as possible.

Once Link started attacking one of his hands, the other hand would retaliate with one of a half-dozen attacks, including a horizontal swipe across the drum, a horizontal slap, a vertical smacking, grabbing Link with a fist, and just trying to punch him directly. All of these did significant damage to Link.

After Link stunned both his hands, Bongo Bongo did one more attack, involving his entire body and both fists charging across the drum towards Link. This attack was unavoidable and largely damaging. While Bongo Bongo is executing this attack, this is the only time the creature was vulnerable, allowing Link to fire an arrow at its eye (which, for the only time during the battle, is open), disabling it, allowing Link to damage the boss by slashing its eye. Though not required, the Lens of Truth allow Link to see Bongo Bongo's eye, making the battle much easier. The Ice Arrows can also be effective during this battle since they enable Link to freeze Bongo Bongo's hands. This is one of the three bosses in the game where the usage of the temple's treasure, the Hover Boots, is not strictly required (one being King Dodongo since you can use the Bomb Flowers instead of your own Bombs and the other being Phantom Ganon since you can use your Hookshot instead of your Fairy Bow).

Interestingly, Bongo Bongo has the largest amount of health out of the all the bosses in Ocarina of Time. This is a record that is achieved either if the player counts just sword slashes or sword slashes and extra weapons hit, ending up with a total of twenty-six and sixty-three hits, respectively.

Video
This clip was provided by lleeoo2010 at YouTube NiBAnBk2LKM&feature=related

Possible Origins
The boss in the Shadow Temple is theorized to be (or have been) a Sheikah. This is because Adult Link can talk to Shikashi near the House of Skulltula, this elderly man states:
 * "A long time ago... There was a man in this very village who had an eye they said could see the truth! Now usually, you have to train your mind's eye most strenuously to actually see the truth... But this fella, no, they say he had a different way of doing things... His house stood where the well is now..."

The shapeshifter monster could probably be this person due to the fact that Bongo Bongo has one eye and was living in the well. His house could have been sent to the bottom of the well, along with certain artifacts (the Lens of Truth, a Sheikah's item). His description says Phantom Shadow Beast, as "phantom" as a "dead person" and "shadow" as "Shadow folk", another name for the Sheikah.

Also Bongo Bongo was possibly a Dark Interloper in the Hyrulean Civil War and was executed, being sent (along with his house) to the bottom of the Kakariko Well. To add to this theory, The Bottom of the Well has various torturing devices, which means this is possibly the place that Bongo Bongo may have been executed in. Another theory proposed is that he was a Twili, but he wasn't imprisoned in the Twilight Realm. Instead he was sealed away in the Bottom of the Well by Impa. It is also possible that before they knew about the Twilight Mirror they bound certain interlopers in distinct places.