MJpoland said:
It helps to tell us what works you know of.
The author Peptuck [https://www.fanfiction.net/u/348055/Peptuck] runs the gamut of genres, from the 'war is hell' novelization of Tiberium Wars, What If Firefly's Book and Wash survived the movie in Foward and what happens when you mash Borderlands with Mass Effect. (Mister Torgue unveiling his new corporate headquarters of Urdnot-Torgue on Illium by blowing up the top ten floors in the shape of a giant flaming middle finger aimed at the headquarters of Hyperion and Maliwan, all the while playing air guitar on live galactic television.)
Hakumei [https://www.fanfiction.net/s/4119917/1/Hakumei] is a Naruto series with a nice twist, Danzo kills off the Hokage with the six year old team 7 plus Hinata, Neji and Sai secretly watching. They escape Konoha, picking up Haku, Gaara etc and it isn't all fun and games (the first winter almost kills all of them). Eventually they are found by a Sannin and plan to take back the Leaf.
To Soar into the Sunset: A Night Fury's Odd Memoir [https://www.fanfiction.net/s/6038952/1/To-Soar-into-the-Sunset-A-Night-Fury-s-Odd-Memoir] A How to Train Your Dragon fic with the POV of a skilled signaler shot down during combat, trying to solve the mystery that killed his father. Oh yeah, he's now being called Toothless to his horror. Lots of snark and a rather nice take on the HTTYD plot.
The Enemy of My Enemy [https://www.fanfiction.net/s/4305125/1/The-Enemy-of-My-Enemy] If you hated what 343 did with the Elites and wanted to see humanity being forced to work with them in order to survive a Brute horde, eventually becoming fire forged allies then the story of the Outer Colony Crassus is for you.
Lost in the Woods [https://www.fanfiction.net/s/4603570/1/Lost-In-The-Woods] Picard gets pissed at Q after the Borg incident and Q decides to teach him another lesson, by transporting the Enterprise into the path of a certain Firefly class transport. Has a sequel dealing with the aftermath of the Enterprise's visit for both universes.
Razor's Edge [https://www.fanfiction.net/s/6049842/1/Razor-s-Edge] A decent novelization of the 2nd and 3rd ME games, expanding on some plot points and locations. Deals with Shepard and Tali.
Flipside [http://www.fimfiction.net/story/50167/Flipside] Spike is the pony, Twilight is the dragon, seems like a standard plot right? Nope, Spike Flail is an up and coming news reporter for the Canterlot Sun, sent to record the 1000th Summer Sun celebration in Ponyville. Meanwhile Princess Celestia is preparing for her last day as ruler...
Those are some of the long creations I've read, there are also tonnes of shorter stories as well like Berseker Hell [https://www.fanfiction.net/s/3315463/1/Berserker-Hell] where a 40k Khornite Berseker finds himself trapped in the Hundred Acre Wood and Caught by the Bolo [https://www.fanfiction.net/s/2957124/1/Caught-by-the-Bolo] where one of humanities homicidal robotic creations (the Cylons) meets one of it's staunchest robotic protectors.