The Stormraven Gunship (also known as The Brick, The Hindenburg Class Gunship, Dorn's Nightmare, The Pig ("I'll stop mutilating corpses when Pigs fly!"), The Anvil, The I Can't believe It's Not Aerodynamic, The Flying Clown Car, The Dakka-TARDIS, The Metal Bag of Holding, and The Dude This Shit Will Not Fly) is a vehicle used by Space Marines in Warhammer 40,000. It is built for maximum air resistance so that the air can never defeat the Space Marines.
Space Marines are, at their core, a surgical strike force, and so they have developed many ways of delivering Marines into precise, heavily-guarded locations. The Thunderhawk can carry a relatively large number of Space Marines from orbit, but it is an extremely large, inviting target. Sometimes, a smaller aerial insertion is what is required, and the Stormraven fills that role. The Stormraven is capable of carrying 12 Space Marines into battle as well as a dreadnought slung from a set of mag-clamps under the tail. Unlike the Rhino, the Stormraven has no restrictions on what models it can carry (besides the Primaris Pretty Boys) but TERMINATOR models count as 2 models and CENTURION models count as 3 models. Pointing out that it would take Time Lord technology to fit twelve marines, sensor equipment, the hardware for the machine spirit, and all the ammo and loading mechanisms for the guns while still carrying enough fuel to engage in planetside ops and return to a spacecraft inside a Stormraven is heresy.
The Stormraven is armed with a twin Assault Cannon, which can be swapped out for a twin Lascanon or Twin Plasma Cannon, a Twin Heavy Bolter, which can be swapped for a Typhoon Missile Launcher or Twin Multi Melta, and Two Stormstrike Missile Launchers. Optionally it can also take a pair of Hurricane Bolters.
TL;DR It's basically a LAAT/i, just bricky.
It used to be that only Grey Knights and Blood Angels armies could take the Stormraven, because apparently, the Stormraven didn't exist when Roboute Guilliman wrote the Codex Astartes, and because the Grey Knights did not see fit to allow others to use the technical plans in the millennia that they have employed the Stormraven (while the Blood Angels only got their hands on some Stormravens in M41), but when the Death From The Skies Compendium was released ALL Space Marines except the Space corgis and Dark Angels gained access to the Stormraven as well. Why they were never mentioned as having it before, they blame it on administratum bureaucracy.
The model was released around the same time as Codex: Grey Knights; its initial entry in Codex: Blood Angels didn't even have a picture. As it was a fairly tough transport capable of taking 12 Marines, it became known as a "flying Land Raider," due to it AV 12 12 12, and was often kitbashed as such. As far as actual preformance goes it's fairly versatile for a flyer, being capable of being given plasma cannons, twin-linked multi-meltas, hurricane bolter sponsons, and a mish-mash of other weapons. With solid armour all around and three hull points, the Stormraven can take as much damage as it dishes out. 8th edition has turned it into a monster. T7 and W14 make it pretty tough to kill. Every formerly twin linked gun is now two separate guns, doubling the volume of fire for most loadouts. Points-wise, it's a fair bit more expensive, but worth the increase.
|Forces of the Blood Angels|
|Command:|| Apothecary - Brother-Captain - Brother-Sergeant - Chaplain |
Chapter Master - Librarian - Sanguinary Priest - Techmarine
|Troops:|| Assault Squad - Devastator Squad - Sanguinary Guard - Scout Squad |
Tactical Squad - Terminator Squad - Veteran Squad
|Death Company:||Death Company - Death Company Chaplain - Death Company Terminator|
|Walkers:|| Contemptor-Furioso Dreadnought - Death Company Dreadnought |
Dreadnought - Furioso Dreadnought - Librarian Dreadnought
|Transports:||Drop Pod - Razorback - Rhino|
|Vehicles:|| Baal Predator - Land Raider (Land Raider Crusader - Land Raider Phobos |
Land Raider Redeemer - Land Raider Angel Infernus)
Predator Tank - Vindicator - Hunter - Stalker - Whirlwind
|Flyers:||Stormhawk - Stormraven - Stormtalon - Storm Eagle - Thunderhawk|
|Allies:||Space Marines - Primaris Marines|
|Forces of the Dark Angels|
|Command:|| Apothecary - Company Master - Interrogator-Chaplain |
Chaplain - Librarian - Techmarine - Deathwing Knight
Dark Angels Grand Master
|Troops:|| Assault Squad - Deathwing - Company Veterans |
Devastator Squad - Scout Squad - Tactical Squad
Ravenwing Black Knight - Watcher in the Dark
|Walkers:|| Dreadnought (Deathwing Dreadnought - Contemptor Dreadnought) |
Contemptor-Mortis Dreadnought - Mortis Dreadnought
|Transports:|| Land Raider (Land Raider Phobos - Land Raider Crusader |
Land Raider Redeemer - Land Raider Ares
Land Raider Solemnus Aggressor) - Rhino - Drop Pod
|Vehicles:|| Bike Squad - Razorback - Predator - Vindicator - Hunter |
Stalker - Whirlwind - Land Speeder Vengeance
|Flyers:|| Dark Talon - Nephilim Jetfighter - Stormraven - Storm Eagle |
|Allies:||Space Marines - Primaris Marines|
|Forces of the Grey Knights|
|Command:|| Brotherhood Champion - Grand Master - Librarian |
Techmarine - Chaplain - Apothecary
|Troops:|| Grey Knight Paladin - Interceptor Squad - Justicar |
Purgation Squad - Purifier - Strike Squad - Terminator Squad
|Walkers:||Dreadknight - Doomglaive Dreadnought - Venerable Dreadnought|
|Vehicles:|| Land Raider (Land Raider Crusader - Land Raider Vortimer) |
Rhino - Razorback
|Flyers:||Stormraven - Stormtalon - Stormhawk - Thunderhawk|
|Allies:||Inquisition - Sisters of Battle|