Got any favorite boss themes? Post them here. Feel free to post YouTube links too, cause I'm always open to hearing new video game music and cool boss themes.

Overture to the End (https://www.youtube.com/watch?v=tGlp2-s-yLg) - From Mario & Luigi: Partners In Time. Plays when battling Princess Shroob. This is my favorite boss theme from the Mario series. Koopa's Theme (https://www.youtube.com/watch?v=MBOsi1sMHoc) comes to a very close 2nd for me cause of it's badassness.

Gangplank Galleon (https://www.youtube.com/watch?v=lS7_tcwsj4E) - Best Donkey Kong boss theme. Thought it was cool that it got remade in SSBB too, but I still like the original better.

Mechanical Battle (https://www.youtube.com/watch?v=4WmtlZVYx48) - From Separation Anxiety. With Guns Blazing (https://www.youtube.com/watch?v=FGYnuAdF3TU&list=PL3048995BAD07442E) also kicks ass.

Vs. Meta Ridley (https://www.youtube.com/watch?v=nLLjibR_c4Q) - From Metroid Prime. Best version of Ridley's them in my opinion. Omega Ridley's Theme (https://www.youtube.com/watch?v=VcpVyER_UTA) is also pretty cool.

Majora's Mask (https://www.youtube.com/watch?v=4AzNTt-boS4) - Probably one of the most, if not the most menacing boss theme I've ever heard.

The Grave Digger (https://www.youtube.com/watch?v=OMJK-yffn5o) - From Resident Evil 3: Nemesis. Probably the most menacing boss theme in the Resident Evil series in my opinion. I always get a chill down my spine whenever I listen to this.

Phantom Ganon (https://www.youtube.com/watch?v=N8g7lxYwIHU) - From The Legend of Zelda: The Wind Waker.

All I got for now...

I'm not sure exactly what time range, if any, you might mean, but I'm gonna give it a go, anyhow...

Face to Face (http://www.youtube.com/watch?v=5SHOvWhti98&list=PL54484A7672FDB135) and Tor (http://www.youtube.com/watch?v=86IxmklUgEM&list=PL54484A7672FDB135) from the game Iji (http://www.remar.se/daniel/iji.php) (The Last Link goes to the page where you can DL the game and the HQ version of the soundtrack.)

I also enjoy listening to the boss (http://www.youtube.com/watch?v=TUGBW3Qc4K4) themes from (http://www.youtube.com/watch?v=_hQzTkv_hck) Super Metroid. Though they can get a bit repetitive.

Metroid Fusion also has a few I like:
-Boss Room (http://www.youtube.com/watch?v=pVffc8czwes) (Not Sure if it counts, since you're not fighting a boss yet! LOL!)
-Serris X (http://www.youtube.com/watch?v=oDjqxwbo7Mg)
-Core X (http://www.youtube.com/watch?v=9SZf0ACRt_Q&list=PLCE419A1BA49FC03B)
-Nettori (http://www.youtube.com/watch?v=2ZJCVuJqOas&list=PLCE419A1BA49FC03B)

And one of the best Boss themes out there, IMHO is Yell Dead Cell (http://www.youtube.com/watch?v=GkWBzXLJXrY) from Metal Gear Solid 2: Sons of Liberty, closely followed by Father and Son (http://www.youtube.com/watch?v=O-XbpCJxM9s) and the Battle Theme (http://www.youtube.com/watch?v=4xHnCtZ_OGg) from the same game.

Perfect Dark had an entire soundtrack in it's favor, and the Boss themes seemed to be a more "urgent" version of the level themes.

Then, going into the 8-bit/16-bit arena, I like the boss music from the following:
-Super Mario 2 & 3
-Ninja Gaiden 1 - 3
-Werewolf: The Last Warrior
-MegaMan 4 (So sue me! LOL!)
-Batman
-Sonic 3
-Forgotten Worlds (http://www.youtube.com/watch?v=PwhLzUijOPc&list=UUx5YkPNQWMLFbv059WGp1sA) (Link is for the Arcade ver, but I played on Genesis)
-X-men & Spiderman: Arcade's Revenge
-Maximum Carnage (especially the Super Villains (http://www.youtube.com/watch?v=U5raE8lvquA) theme) (I deliberately used this version so you can see WHY I like this track!)

...and at this point, it starts to become a list of games I've played over my 31 years of life.

There is no time range. I do know about the Metroid, Mario, and the MGS2 ones. The Super Villains theme actually sounds very similar to Underground City (https://www.youtube.com/watch?v=QFVxFnDuMdw) from Separation Anxiety.

Don't have too many. Will name what's in my head at the moment though.

Super Mario Bros 1-3
Super Mario World
Turtles In Time
Killer Instinct
Street Fighter 2
Maximum Carnage

- Battle With Lord Mei-oh (http://www.youtube.com/watch?v=ARUswVuRaGI) [Tenchu: Stealth Assassins]
- choir of curse (Boss BGM -type1-) (http://www.youtube.com/watch?v=2-lqNeL1Rf4) [Chaos Legion]
- Hiruko (http://www.youtube.com/watch?v=M73JHnx13LE) [SHINOBI ~ PlayStation 2]
- Phoenix (http://www.youtube.com/watch?v=E28ie3Xj4ek) [EHRGEIZ: God Bless the Ring ~ Quest Mode]
- The Final Hour (http://www.youtube.com/watch?v=3coOvRq_vkk) [Onimusha 2: Samurai's Destiny]
- Ultra Violet (Nelo Angelo Battle) (http://www.youtube.com/watch?v=atGcliA-HNw) [Devil May Cry]
- BUST THE BEAST (Goatling/Phantom Battle) (http://www.youtube.com/watch?v=ADpec7QkoIw) [Devil May Cry 2]
- Beast Legacy (http://www.youtube.com/watch?v=n45Ks4ctmJ0) (Maybe not a Boss-theme in the strictest sense of the word, but it's the track you hear on the last stage of Story Mode)
- [B]Theme of GOUKI remix (http://www.youtube.com/watch?v=BGUx6t87j-U) [Capcom vs. SNK 2: Mark of the Millennium]

Pokemon Red/Blue - Final battle against Gary
Anything from the Tohou series
Megaman X5 - Final battle with Sigma
Final Fantasy 8/7 - Final battles

FFVII
One-Winged Angel

FFVIII
Premonition
Maybe I'm a Lion
The Legendary Beast
The Extreme

FFIX
Dark Messenger
Necron's Theme (Final Battle)

Chrono Trigger
World Revolution

FFVII
One-Winged Angel
...
Chrono Trigger
World Revolution

I would have added these if I'd thought about it, but it also reminded me of the FF6 Battle Music, which I'll add to my list...

Boss Battle 2 - Chrono Trigger Music Extended - YouTube (http://youtu.be/UCcUjT9plNE)
Megaman Battle Network 4 - Battle With Myself ~ Boss Theme (http://www.youtube.com/watch?v=R0GLuDuiSzU)

Boss Battle - Learn with Pok�mon: Typing Adventure (https://www.youtube.com/watch?v=UMsxw_u8664) - I'm sorry, this one is just... WHY DOES A TYPING GAME HAVE SUCH AN EPIC BOSS BATTLE THEME!?!

Sonic 2 - Final Boss (https://youtu.be/x4L4TSrDB4M)
Castlevania: Symphony of the Night (Saturn) - Bloody Tears (https://youtu.be/tgkxSkF7QOU)
Secret of Mana - Oracle (https://youtu.be/TCUdhcRQMC4)
Contra: Shattered Soldier - A True Last Boss (https://youtu.be/obayUKdauS8)
Contra: Shattered Soldier - Survival of the Fittest (https://youtu.be/N_gRBR-K-nY)
Sonic Adventure - Open Your Heart (https://youtu.be/qH_MCPcjxP0)
Sonic Adventure - Fight for My Own Way (https://youtu.be/JVqNzDRSLyY)
Super Metroid - Mother Brain (https://youtu.be/nBYlXtRjj34)
Super Metroid - Samus' Theme (https://youtu.be/Hx4Gsp5rcwM)
Super Contra (arcade) - Hotter Than Hell (https://youtu.be/LumT49MNcAI)
Super Mario Galaxy 2 - Decisive Battle (https://youtu.be/8vxLzHSfnxk)
Super Mario Galaxy - Bowser (https://youtu.be/IObwdOCAfdU)
Megaman X8 - Last Boss (second form) (https://youtu.be/urdyRHAzIFM)
Raiden DX - Go to Blazes! (https://youtu.be/RfiOD_ctjcQ)
Final Fantasy 6 - Dancing Mad (https://youtu.be/JbXVNKtmWnc)
Super Mario RPG - Fight Against Kajidoh (https://youtu.be/HBRrzwvpaNQ)
Mega Man 2: The Power Battles - Mecha Dragon (https://youtu.be/d4IQL5OMRa8)
Super Castlevania IV - Dracula Battle (https://youtu.be/AbRWDpruNu4)
Super Castlevania IV - Simon's Theme (https://youtu.be/pQVuAGSKofs)
Castlevania: Dracula X Chronicles - Dance of Illusions (https://youtu.be/_SWPBRpPfyc)
Castlevania: Bloodlines - The Vampire's Stomach (https://youtu.be/llWhTJG6H-4)
Castlevania 64 - First Struggle (https://youtu.be/X2M5J1xzB7o)
Final Fantasy Origins - Battle Scene (https://youtu.be/bgDBa_eLlW0)
The Legend of Zelda: A Link to the Past - Ganon (https://youtu.be/LfISliRCnO0)
The Legend of Zelda: A Link Between Worlds - Yuga Battle (https://youtu.be/Oxl-n80bq_Y)
The Legend of Zelda: Link's Awakening - Last Boss (https://youtu.be/554DNmPdbCc)

That's probably enough until I think of more.