I just wanted to know what people's favourite mods that adds stuff from other franchises?

Personally, some of mine are:
Decer's port of the S.T.A.L.K.E.R weapons and armour are pretty awesome. S.T.A.L.K.E.R has been one of the closer franchises to Fallout and I'm personally a big fan of them so it's a pretty awesome mod.

Cpt Rex, Tank Girl and jesusp have made some great Star Wars mods and as a Star Wars fan  (as are many of us) these are great to have.

Tesvixen made an Adam Jensen race and armours mod, also his .357 revolver, it's pretty nice to have Adam Jensen in the Mojave

So what are yours?

I'm a bit biased, since I port stuff from other games all the time. I had fun adding Hitman
Absolution's sniper rifle to NV (looks great and fits well in-game).

But I would have to say for other people's mods I like Milennia's weapons and Gerokeymaster's Claptrap
Companion (though it uses some in-game assets, the premise is from a different franchise). I haven't used
items by Dragbody or Cpt Rex yet, but will do it if I get a break from making my own mods! ^_~

If I had to mention one that was a "must" for me, before the Multiplayer returned for it so I reverted it back to it's Vanilla setting, it would be the mod for Star Wars Battlefront II (2005) that changed the CIS to the Empire in Coruscant. Granted it's a shame that they didn't have their dialogue, but good enough that the Clone Troopers recognized them as the Empire.

There was a mod a while back for civ v that allowed your borders to grown into another civ if your culture and or empire was happier than theirs. It was a nice counter to a blobbing civ if they were taking over mass amounts of cities their culture and general happiness were likely inferior.

I lost WAY too many hours days of my life to Battlefield 2's Project reality and their team.

But as far as stuff brought into Fallout, I really have to tip my hat to GhostCR0 and U653748. Two of my favorite franchises ever are Star Wars (I still miss my EU - apparently now called Legends) and Halo (At least prior to 4 & 5) and they have done an absolutely amazing job bringing them into FO4.

Once I get some more free time I plan to jump back into FNV, and can't wait to try some of the stuff by Cpt. Rex and Tank Girl. Their Star Wars ports look nothing short of amazing!