Good call! It even had a twin, IIRC…TRM
Surprised that nobody has mentioned Mathew Quigley’s (Tom Seleck) big single shot target rifle in “Quigley Down Under”. It was easily the real star of the movie.
Green Lantern’s Power Ring.
Clint Eastwood has co-starred with some very cool guns.
Remember the Mauser Broomhandle in “Joe Kidd?” There was also a nice cameo by a Savage Model 99.
Just thought of another cool one! The Walker Colt that Gus uses to such great effect in “Lonesome Dove.” Call had a Henry Rifle but it didn’t take on the mythic importance of the Colt.
Speaker-to-Animals’ variable-sword in Ringworld. Cuts through anything! But it doesn’t stack up against Nessus’ tasp! 
My personal favorite of his old school old school pistols, the Remington 1858 New Army from Pale Rider. I’m sure lots of folks were shocked to discover the idea of a speed-loader for revolvers was that old!
CMC fnord!
All of Clint’s guns here, and the must have link for this thread, the internet movie firearms database.
Hell, all the named objects in LOTR are characters.
In the 1983 film Utu, about a Maori rebellion in New Zealand in the 1870s, one of the characters is a British colonist whose wife is killed by rebels. He goes more or less insane for revenge, and devises a sort of super-shotgun made out of eight shotguns in a frame, with a jerry-rigged mechanism to fire them all simultaneously. (Dealing with the recoil takes him some practice.)
Peter North costars with a large caliber weapon in his films.
Wyatt Earp’s Buntline Special.
Id like to nominate those lazer bolo’s from the original Battlestar Galactica, as well as the colonial blasters. I like the new series but, the originals just say you know you been kissed.
The assault rifle from Gears of war, the one with the chain saw bayonet and in the same vibe, the chain sword from the 40k universe.
Lastly for now, that light hearted romantic pig sticker from the mask of zorro.
Declan
No one’s mentioned Ice-Nine?
Sergeant Harper’s seven-barrelled naval musket from the Sharpe series.
A minigun; he called it “Old Painless”. Same as the one the Terminator used in Terminator 2.
“Ol’ Painless is waiting for ya!”
Heh! I’m not sure it’s fair to count sentient objects that actually ARE their own characters. Coinspinner wasn’t just a weapon, it was able to take action to suit its own ends, even against the intent of the wielder.
Well, that would also exclude Stormbringer, the Soft Weapon, the Krang, and a fair number of other weapons mentioned in this thread.
Well, I’ll be damned. A gun you can stop by putting your finger in the barrel. Bugs Bunny vindicated at last. Does Mythbusters know about this?
Speaking of rabbits, the singing sword from Who framed Roger Rabbit?.
By astounding coincidence, I just read an article about the Gyrojet this morning in the latest Bathroom Reader.
Some Discworld entries.
The Gonne from Men at Arms.
Detritus’ enormous siege weapon “crossbow”
The Piecemaker.
But not Corporal Carrot’s sword. There’s nothing special about that at all.