Octavo is a musician and magician who played for the King. Fearing the return of Ganon, Octavo bewitched the King and attempted to steal the Triforce. However, upon being touched, the Triforce split. Despite this, Octavo was able to enchant his Lute and transform it into the Golden Lute, granting him more power. Using this power, Octavo sealed Hyrule Castle, cursed the inhabitants of Hyrule to follow a rhythm, and summoned an army of monsters across Hyrule. He also placed various Instruments deep within the dungeons of Hyrule to prepare Four Champions who could combat Ganon.
In addition to bewitching the King, he also bewitched Barriara to fall asleep in Gerudo Village, froze Lake Hylia, and summoned monsters to the Kakariko Crypt. To create the Golden Lute, Octavo stole the Thread of Wisdom, Thread of Courage, and Thread of Power from the Fates.
Octavo can be encountered at the end of four elemental dungeons in Hyrule, attempting to infuse the elements into his Instruments to create his Four Champions. When he is first encountered, he challenges Cadence, Link, Yves, or Zelda in combat against his first Champion. When met for a second time, he vows to not make the same mistake as before, pitting the heroes against his second Champion. During the third meeting with Octavo, he insists that the heroes will never be capable of fending off Ganon. In the fourth meeting, Octavo reveals that he is attempting to amass an army to fight Ganon and summons his final Champion in an attempt to make the heroes recognize this.
After the four Instruments have been collected and Hyrule Castle has been infiltrated, Octavo greets the heroes and forcibly reclaims his Instruments to empower himself. He then questions if the heroes can prove to be his Champions instead, prompting them to battle him.
Upon Octavo's defeat, a Portal will appear and spirit away the Golden Lute. Octavo will blame the heroes for this and lament that Ganon cannot be defeated without it. He then travels to the Future World, 25 years forward to a time when Ganon has taken Hyrule. In the hopes of stopping Ganon, Octavo challenges him to combat, only to lose. Octavo is not seen after the defeat of Ganon.
Octavo is fought on a stage surrounded by monsters and possessed Guards. Using the power of the Golden Lute, Octavo summons monsters by channeling the various Instruments at his command. When these monsters have been exhausted, he will switch Instruments. Upon exhausting the Glockenspiel, Bass Guitar, Maracas, and the Oboe, Octavo will summon random sets of monsters with the Golden Lute until he has sustained enough damage. When he is struck after summoning random monsters, damage will be dealt to the Golden Lute, which has six Hearts. In addition to summoning monsters, Octavo can conjure rows of magical Swords or Hammers in purple or green to damage Link and Zelda respectively. Octavo can also summon fireballs, which he casts in the shape of a chevron.
After the Golden Lute has been dealt enough damage, a Portal will appear. The Golden Lute will fall into the Portal, ending the battle.
- Cadence admits that Octavo reminds her of the Necrodancer, the primary antagonist from Crypt of the NecroDancer.
Octavo's name is derived from octave, an interval between harmonic pitches of different frequencies.
- "I was caught off guard here by a strange man, Octavius? Octavoo? I'd love to teach that guy a lesson!" — Barriara (Cadence of Hyrule)
- "Octavo" — N/A (Cadence of Hyrule)
- "Are you wondering what's causing our movement to be controlled? It all starts in the future...or was it in the past?" — Fate (Cadence of Hyrule)
- "In any case, it's the power of the Golden Lute. The magician Octavo can use it to compel people to follow his orders! He must really like dancing..." — Fate (Cadence of Hyrule)
- "A purple-haired man came in, took over the castle, and put the king to sleep, saying it was for "the greater good." Things don't look so good out there, though..." — Hyrulean Soldier (Cadence of Hyrule)
- "Octavo played a song on his lute right before Barriara fell asleep. Maybe we could wake her up with a different song?" — Gerudo (Cadence of Hyrule)
- "Some wizard guy came by and messed everything up. He's in the Frozen Grotto under the lake if you want to help. No pressure though." — Prince (Cadence of Hyrule)
- "I saw a strange man with a lute doing something suspicious over near the crypt." — Hylian (Cadence of Hyrule)
- "I'm sorry I can't tell you more. The future is cloudy... My visions have been limited since Octavo stole my Thread of Wisdom." — Fate (Cadence of Hyrule)
- "My Thread of Courage was stolen by Octavo. He used it to construct a lute. What? Of course I knew it was going to happen! But I couldn't do anything about it. It's not easy to change one's fate, you know." — Fate (Cadence of Hyrule)
- "I recently foretold Octavo's future. I told him he would meet his demise at Ganon's hand in the future. He didn't like it, but that's what I saw! Serves him right for stealing my Thread of Power..." — Fate (Cadence of Hyrule)
- "Greetings, holder of the Triforce. My name is Octavo, and Hyrule belongs to me...at least for now. If you don't like it, see if you can stop me! I'll be waiting at the top of Hyrule Castle. You'll need to find all 4 of my magic instruments to reach me there! Now allow me to introduce the first of my champions." — Octavo (Cadence of Hyrule)
- "Looks like you got lucky the last time. I'll not make the same mistake again. Face my second champion!" — Octavo (Cadence of Hyrule)
- "Perhaps you're stronger than you look. Not that it matters... You'd never be able to defeat Ganon. But are you strong enough to defeat my third champion?" — Octavo (Cadence of Hyrule)
- "You again! Still haven't given up? I'm doing this for your own good, you know. We'll need an army when the time comes to face Ganon. My fourth champion will beat some sense into you!" — Octavo (Cadence of Hyrule)
- "I prepared my champions to face Ganon, but things have taken an unexpected turn. I'll be taking back my instruments now." — Octavo (Cadence of Hyrule)
- "Perhaps I require a new champion. Let's find out if you are the Champion of Hyrule! Prepare yourself!" — Octavo (Cadence of Hyrule)
- "Where did that portal come from? What have you done?! You fools! Without my Golden Lute, how will we defeat Ganon? We have only one final hope..." — Octavo (Cadence of Hyrule)
- "Cadence! You need to get yourself to the future immediately! ... FURTHER to the future that is. 25 years, to be exact. That's not so far, in the grand scheme of things." — Fate (Cadence of Hyrule)
- "Ughhh... I couldn't...defeat him...alone..." — Octavo (Cadence of Hyrule)
- "I'm beginning to think that I'll never get home with Octavo around. He reminds me of someone from my world that I really don't like! Why don't we join forces to take him down?" — Cadence (Cadence of Hyrule)