Ouroborus- Bravely Default- Mainly for the creative use of spotpass.
Perfect Chaos- Sonic Adventure- Doesn't really hold up, but the combination of the visuals and music were pretty epic in 1999. Having a Sonic Boss where your objective is to run real fast was a smart choice.
Eggman- Sonic Colors- Purely for the theme song.
Xenmas- Kingdom Hearts 2- Kingdom Hearts did an amazing job of taking what was honestly a pretty basic battle system and making it feel cinematic and epic. Nowhere better than in the climax of Kingdom Hearts 2.
HHH- WWE Day of Reckoning- In wrestling and videogames, the key to a great climax is building a grudge between the protagonist and the antagonist. In the storyline of this really underrated game, HHH is the villain, manipulating your character from the beginning. When you eventually get the chance to beat him for the championship, it's pretty awesome.
Sandman- Punch Out!!!- A simple but challenging test of the skills you've learned over your boxing career.
Jeringha- Wonderful 101!- Platinum games is great at doing ridiculously over the top final boss battles. This one is my personal favorite.
Undertale- Whichever route you go with, the final boss is an appropriately epic culmination of your character's lust for power or unflinching kindness. Also features two of the best tracks in gaming.

Demon King Ganon at the end of Tears of The Kingdom. So satisfying to actually kill Ganon for a change instead of just sealing him somewhere.

Also I forgot to add the Street Fighter final boss. That guy I have beated so many times and he has the best one liners. M BISON!

Obviously, this thread has plenty of spoilers already. I'll list some games without the boss name, though in case it prevents some people from being spoiled.
In no particular order
Super Mario Galaxy
Super Mario Galaxy 2: One of the parts might seem like a letdown for some but the music is fire.
The Legend of Zelda: Ocarina of Time - Mainly for the first half of the fight.
Fire Emblem: Awakening
Paper Mario
Paper Mario: The Thousand-Year Door
Star Wars: Knights of the Old Republic
Star Wars: Knights of the Old Republic II
Persona 5: Typical final boss probably is worthy but the final boss of the 3rd semester stuff in Royal probably is as well.
Marvel's Spider-Man
EarthBound: Nightmare fuel
Mother 3
Final Fantasy VII
Final Fantasy VII Remake
Ghost of Tsushima
Luigi's Mansion
South Park: The Fractured But Whole: It's a pretty funny fight and still fun.

Virgil, Lord of the Cinders, Gherman from Bloodborne, Bowser from SMG, Ganon(dorf) from Zelda TP, final bosses of GOW 3, GOW PS4 and GOEbRagnarok, Sepiroth FFVII remake, and Spiderman is final boss come to mind.

King Allant. Fits lore so well.

Ravenbeak from Metroid Dread.

The build-up to the fight, superhard but so satisfying, Samus going mental, the escape sequence. Just brilliant.

There have been many good ones. But, I find that most final bosses disappoint me because they're too easy.

A recent one I liked that comes to mind is Chaos Elfilis from Kirby and the Forgotten Land. Relative to the easy gameplay throughout that game, the final boss was a nice step up in challenge level.

I also enjoyed Ganon at the end of TotK.  However, I beat him on my first try, which is a negative.  Final bosses should be more challenging.  

I think sword saint isshin takes the cake