Do you have a favorite crossover fic? I'll start as I have several:

1. The Trials of High School and The Lessons of Life- both by Kamari Turen (6teen and total drama)

2. Total Drama Ultima-Nick The Ultima Sword Wielder (total drama and various cartoons and animated movies. And for some reason, a bit of Sky High)

3. Fairly Odd Drama-kirbykid13 (Total Drama and Fairly Odd Parents)

4. Pokemon Challenge- I can't remember the name of the author (Pokemon and Professor Layton). It's oddly funny, especially Layton being slightly out of character.

The last crossover fic I ever read (and truly liked as well) was Mass Effect: Renegade. The writer crossed the Mass Effect universe over with the Command & Conquer universe's Tiberium timeline. The result? The Systems Alliance being replaced by GDI, The Reapers taking place of the Scrin, Nod spreading their organization throughout the stars, and the Citadel species drastically changing their approach towards humans and military viewpoints as well.

And the crazy thing? A part of me wants to see this crossover happen because both universes could fit each other quite well, and to top it off EA AND Bioware now owns the rights for both, meaning that it could totally happen!

edited 11th Jul '12 3:02:07 AM by SgtRicko

When There Was A Tommorow is without a doubt the best Halo-Mass Effect crossover on FF.net. I also like The Last Spartan, which is another great Mass Effect-Halo crossover.

The best crossover is probably Diablo: Lord of Confusion. First off, it's complete, which is something a lot of crossovers fail at (much more often than non-crossovers). It mixes the two worlds well, and it's got a good mix of funny and drama.

I'd say The Man With No Name (AKA A Life Less Extraordinary), a brilliant Firefly / Dr Who crossover. The author really nails the voices of every character.

edited 11th Jul '12 4:41:20 AM by Gaunt88

Fallout:Equestria. Obvious really.

Links, which is sorta like Crisis on Infinite Earths for the Zelda franchise (and therefore, I believe, counts as a Massive Multiplayer Crossover).

Some of my other favorites include Nanoha Takamachi of 2814, and Rosario To Kiva.

Ed, Edd, n Eddy/Nightmare Before Christmas. The ones by AMX (Fanfiction.net) are very interesting. In fact, many of my favorite crossovers are crossed with Ed, Edd, n Eddy.

There's an old fic out there that was a multi-crossover of Yugioh, Digimon Tamers, Pokemon and Card Captors. The plot was rather nonsensical and it ran on Rule of Cool, making up the rules of the four-way card game as it went along, but it was very fun. You've got Rapidmon fighting Black Luster Soldier, Dark Magician fighting off a Giant Gengar, Sakura dueling Kaiba, Ash and Rika ship tease while Joey and Henry hang out. Also an epic final battle with a fun twist to the villain taken straight from one of X-Men's infamous crossover villains.

@Anime Badger: Can I recommend Metroid Prime: The Ed Hunters then? It's my favorite, and it's probably one of the best-written things on the site despite its seemingly-impossible premise.

Shame it hasn't been updated since 2010. The author insists he will finish it though.

edited 23rd Sep '12 11:54:03 AM by Anomalocaris20

Excellent idea. It must be done.

My favorite crossover fic would have to be The Titans and the Lost Boy and it's sequals, Dark Titans and Reflections Lost On A Dark Road by Lathis (and in the case of RLOADR, Captain Chryssalid). TTLB is a crossover between Teen Titans and Ranma ½, which expands into a crossover between Ranma ½ and the DCAU in Dark Titans. Then, in Reflections Lost On A Dark Road, it crosses over with another fanfic, The Road To Cydonia (which is itself a crossover between Ranma ½ and X-Com). Oddly enough, Reflections Lost On A Dark Road ended up being significantly longer than The Titans and the Lost Boy, Dark Titans, and The Road To Cydonia combined.

There's also Unequally Rational And Emotional, by Over Master, which is Mahou Sensei Negima! fic that turned into a crossover with Sayonara Zetsubo Sensei, Bleach, Puella Magi Madoka Magica, Neon Genesis Evangelion, Fate/stay night, Batman, Mahou Shoujo Lyrical Nanoha, Sailor Moon, Darkwing Duck, and several other series, with a ridiculous number of cameos (many of which I've probably missed.

edited 4th Dec '12 9:04:43 AM by Hyp3rB14d3

It's not what I'd call a good fanfic, but I do have a soft spot for All the Stars in the Sky. It's a Total Drama Island/Warhammer 40, 000/Tengen Toppa Gurren Lagann crossover featuring, among other things, a new Total Drama series taking place on a Fire Nation airship, the forces of Chaos trying to claw their way into the Total Drama universe through Rossiu's head, and Kamina leading a band of Orks that he's beaten Noblebrightness into.

edited 12th Dec '12 1:16:32 PM by Wittgenstein

All the Stars in the Skies is a nice crackfic, I corroborate the recomendation. Though I wish the author could update, he told me he's still working on it.

Project Ignition. 'Tis a Muv-Luv Alternative and Armored Core crossover. ... I swear I'm not shamelessly selfpromoting.

Undocumented Features. Well, that's an easy one.

Truth and Agony is another one I like. Crossover of the two Yuris, Kannazuki no Miko and and Utena. Perfect.

Going Native; ST:TNG/BSG crossover. Does not involve any feel-good asskickings. Respectful to both sides. Pretty much the only one I can name that does both those things.

Harvey Birdman vs. Organization XIII, crossover between Kingdom Hearts and Harvey Birdman, Attorney at Law. It's a quick fic, over 10k words in a few chapters, but the most interesting thing I found is that it was a failed attempt at bash fic. The author hates Harvey due to lack of understanding how his show works, but he ended making something with Original Flavor and Hilarious in Hindsight, because Harvey goes to The World That Never Was to arrest Xemnas because his Ethereal Blades violate copyright from Star Wars. And guess what happened this year?

Forgive me if I mess-up some titles. I honestly couldn't tell you categorically why I like these fics too specifically, I just like 'em.

Shinji the Mighty, a Neon Genesis Evangelion/Birdy the Mighty fic.

Mass Effect: Clash of Civilizations, one of the better Halo/Mass Effect fics.