I'm curious. Do my fellow GMs have signature touches in their campaigns?

I have a few notable traits in mine:

A series of NPCs named things like Slippery Pete, Toothless Joe and Gentleman Jim. Slippery Pete and Toothless Joe are especially signatures of mine. Slippery Pete is generally a criminal, usually a career thief and Toothless Joe is, for want of a better descriptor, an old prospector. Gentleman Jim is generally a thief with pretentions of sophistication, often at odd with Slippery Pete. They're never very prominent in the narrative, but I hear from time to time that they make appearances in other people's games.

Faux 18th/19th century society - If I have any leeway to interpret the society of my game world, then it is probably going to resemble late 18th or early 19th century society. People are going to have well developed sideburns and tall collars and, if they are personages of any class or distinction, refer to each others with honorifics. They will talk of writing letters to the governor or politely invite adventurers to (actually roleplay) having tea and make polite small talk (that actually happened once. At an adventurer's league game. It was a riot.) Not everyone is out of a Jane Austen novel, but some people are. Lost Mines of Phlandelver I ran closer to a Spaghetti Western (because that module is absolutely a western: one street town, bandits overrun it and hassle the drifters passing through, bounty board, cowardly mayor who dissuades heroes from causing any trouble, the whole motivation of the adventure is a map to a lost treasure), but Westerns are still mostly set in the 19th century. It's just so much fun to use all this slightly archaic language: If injury is given, sir, I shall demand satisfaction.

Celebrity Impersonations - I have a gift for mimicry, so really just so I can remember which voice I did for each NPC, I tend to give them a celebrity voice if I can. Especially if they are important. Players tend to react well if the rat-like villain talks like Wallace Shawn or the ship captain talks like Sean Connery. Hardly unique to my games though.

What about you guys? What qualities keep sneaking into your campaigns?

For some reason, there has been an Inn in every Campaign world called The Ragged Feather.

It was an important location in the first campaign. In the second campaign, when I got to the name of the local Inn, someone shouted out "The Ragged Feather!".

Since then it's become a fixture in every campaign world, along with the family running it. They all might alter slightly to fit into the culture, and the name might change into the local language, but it's still always there.

One of my players played a barbarian named Angus in our first ever campaign. Since then, every character he's made has been Angus. Not a different version but THE SAME Angus every time! His backstory now includes pissing off various deities across campaigns and getting jettisoned across the multiverse. So every campaign, he starts off being dropped off in this dimension with his power sapped, but all his memory from previous (unrelated) campaigns.

So my campaigns' most consistent running jokes is the PC itself lol 

I have an NPC who has been in every game I've run for the past 8 years or so, Aerik. He's been a basic Tavern owner, a source of information, a quest giver, a patron, and a guild leader. He's become so much of a figure that I was asked/begged to make him into a PC for Curse of Strahd. So, an NPC now has an epic plane hopping back story to explain how/why he's got so much information about everything. 

As a fun side note, he has a tic where he's always found standing behind the bar polishing a mug. I made it up as a way to make him immediately recognizable for repeat players. It just so happens that there is an NPC in the 5e version of Curse of Strahd by the name of Eric who is a tavern owner that you meet as he's behind the bar polishing a mug. My DM was convinced that I had just stolen the idea until it was found out that this NPC was a recent addition, my Aerik predated him!

Quote from OboeCrazy >>

Dwarves all have New York City accents. Mostly upper east side, but if I'm having a bad accent day they can turn into New Jersey commuters.

 That is amazing. Bravo, Madam. I applaud you.

All my players at some point meet Mary the Dwarf, he sounds a bit like Foghorn Leghorn and is master Tailor/smith that will try to sell them a chicken suit(either feathered or Iron) for a masked ball or festival.  He also laments about wanting a tougher name, like Alice.

Old, retired PCs from previous campaigns are now rockstar high level NPCs (like superheroes) that new PCs hear about and sometimes even meet. I think it’s fun that my current friends’ characters are running around in the same world in which my high school friends ran around. One day my current PCs will be those superhero NPCs that my future friends will hear about in game.

Quote from IamSposta >>

Old, retired PCs from previous campaigns are now rockstar high level NPCs (like superheroes) that new PCs hear about and sometimes even meet. I think it’s fun that my current friends’ characters are running around in the same world in which my high school friends ran around. One day my current PCs will be those superhero NPCs that my future friends will hear about in game.

 I have moved in this direction myself. My friend is running a game with one of my old players, so I wrote this magic item that was... Well:

Crumpet O’Hanlon’s Guide to 101 Problems: Goblins, Spiders and Shalka - Crumpet O’Hanlon’s Guide to 101 Problems is a compendium of various creatures encountered by the author on his adventures. Those expecting in depth tactics are libel to be disappointed by the contents.  Most of the entries read roughly like this: Step 1) Hit it with magic sword. Step 2) Repeat until dead. A few entries deviate from this pattern. On the page titled Grey Ooze, it only says "GOD FIST." On the page titled Glass Staff, the page remains blank. The page on Shalka has a crude drawing of what looks like an overripe tomato-- or maybe a very bad drawing of a tiefling and it says "kill until dead. Then kill again." Lastly, the page titled Smash has only the words alcohol poisoning posed as a question, as if the author was contemplating potential methods. The tome costs, what some might think is an exorbenent sum at 10 gp, but rumours suggest that it has sold very well so far.

As an action, can be thrown to deal 1d6 damage. 1d8 if used against Shalkas. It is unfortunately not destroyed from use.

Shalka was this player's character (Tiefling Sorcerer), who, after the player decided to exit from the group, (quite in character) stole the current haul of loot and left the party, only to show up in the final dungeon of LMOP and got dead-ed. The ex-player was pleased with  this outcome. So the gnome bard, Crumpet, ended up holding a grudge against Shalka, wrote a book detailing how to kill his many foes (Smash is another party member who quite likes the cups.) This tome is going to show up in my friend's game just to shock the old player. But I liked the concept of a big thick book that people only buy for its heft so much that I decided it will be a fixture in my own campaigns hence forth as well. Now I am determined to make a library of living references to other games to build up my Forgotten Realms experiences.

@Oboe: Some of my current players are returning players and their old PCs might make a cameo. 😉

@Verenti: Where can I get a copy?!?

Quote from IamSposta >>

@Verenti: Where can I get a copy?!?

 Anywhere where books or paperweights are sold!

I don’t have any telltale specifics that are added to my games, like NPC’s or taverns, but I do have a tendency to gravitate towards some kind of horror or ambient terror in my games. I’ve genuinely scared my PC’s quite a few times (which I’m very proud of), but at the same time I’m trying to move away from my “comfort zone”, so to speak. 

I have Maurice and Maureen Shamblebot, a husband and wife pair of artificers, who pop up in all my game runnings. These two gnomes run Mo's Tuff Equipment and More, a traveling shop that has a main branch in Sharn.

While I have other shop owners and such, none have brought more delight to my players then these two and I am constantly asked if Mo is in town.

While I try to vary NPC accents as much as possible, all my dwarves seem to end up Scottish. I can do passable American, Cockney, Received British, Yorkshire, Cornish, Irish, French, German, Russian, Polish, Indian, and Middle-Eastern accents, every time I voice a dwarf it slips into a Scots burr. 

My other signature is that there almost always ends up with something vaguely Lovecraftian in my campaigns. I can't seem to help it. :)

Quote from Aldaron >>

My other signature is that there almost always ends up with something vaguely Lovecraftian in my campaigns. I can't seem to help it. :)

 ohhh, tell me more.

I'll add backstory elements of characters that never got explored. For example, in a Curse of Strahd game, we had a druid that was also a pirate who was captured by a red dragonborn with two giant hyena pets. That's going into my homebrew.

For my personal signature, as a nod to my favorite PC of mine, Gob Sunmeadow, Pelor and the sun are everywhere. Temples, designs in pastries, etc.

There's always a faerie dragon for the PCs to meet. Always.