The crossover is a staple of science fiction fandom: it's the only way to answer age-old questions like, "The Enterprise or the Millennium Falcon?" There have even been canon crossovers, some of which have gone well and some of which...didn't.

By their very nature, the options for crossovers and fusions are endless. Here are ones that never made it to screen or page, but did make fantastic art.

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Top image: Downtime in Spacetime by Either-Art at deviantART

Ten and Wheatley by radiohamlet at deviantART

HP-Naruto crossover by Phii-chan at deviantART

Mis-firing Portkey by tripperfunster at deviantART

WWACC Tron Pilgrim by dyemooch at deviantART

The Doctor and Marty McFly by Obsidian at Commissioned Comic

Predators by JoannaJohnen at deviantART

The Host 2 by Leah Rosenthal

SCI-FI CROSSOVER by crisdelara04 at deviantART

Simply walk into Mordor by ferret42 at deviantART

Muppets Kick Ass by StrangelyDrawn at ArtBreak

The Prince and the Lord by JaviDLuffy at DevianART

Ahsoka and the Beast by clc1997 at deviantART

hulk vs hellboy by gabahadatta at deviantART

One of the Star Wars Movie Posters by Matthew Ranzetta

Batman VS. Darth Vader by Dave Dorman at Loyal K.N.G.

Star Trek vs Dr. Who by Summerset on deviantART

Part of the Mural by Jim Mahfood at's office, via Comics Alliance

Collab of Badassery by Daniel Araya and Enrique Rivera via Venture Bros. Blog

Black Shirt Boogie by rahzzah featuring Brock and Wolverine via Venture Bros. Blog

Darth Vader vs. Aliens by David Hillman, inks by Mark McKenna and colours by Tom Chu via How to Carve Roast Unicorn

by Misha via Geek Art

Rodney McKay as The Doctor by WolfenMoondaughter at deviantART

batman sesame street by Matthew Benkner via you love meg

Spacetime's Finest by Dean Trippe at etsy

Yellow Lantern Zim by Arqueart at deviantART

Poker Game by Stardamsel at shirt.woot

Oh No: Superman UK by Aviv

USS Millennium Falcoln by Phil Noto

SPN - Hellboy crossover by JoannaJohnen ay deviantART

The Dagobah Connection by Peter de Seve via Loyal K.N.G.

Law & Order: UFP's Detective Odo by Jake

The Doctor meets the Doctor. by Furrysketch at deviantART