The mayor of Pelican Town, often seen visiting the local businesses or gardening.
Lewis.

One of the most common secrets (Since its embedded into the game and placed down at your feet), is that these two villagers are seeing each
Marnie and Lewis
This town is where most villagers live and work.
Pelican town!
Sebastian, our loveable basement dweller, will help you play the Stardew valley version of this game in his 6 heart event
Dungeons and Dragons!
At the start if this year, Grandpa visits the player and gives them a judgement, lighting candles and possibly giving them a iridium giving statue.
Year 3
One of the most popular dateables, she is blonde and loves to shop, despite not having a job.
HALEY!!!!!!!!

Caroline is rumored to have had an affair with this outsider and Abigail is actually his daughter. we are hinted in on this from dialog from Caroline, Pierre, Abigail, and this outsider himself.
The Wizard! (Rasmodius is also ok)
This city is the bigger counterpart to the valley, many villagers talking about how they moved away from there since they didn't like the city, and it's where the player is most likely from.
Zuzu city!
In Vincent and Jas's 8 heart event, you will see them in the forest and they will give you the power to sell these springtime foragable for x5 gold.
Spring Onions!
Our crazy blue haired girl Emily, is known to love this type of bird and takes one it. This is a favorite bird type she shares with Leo.
Parrots
Married to the the storeowner Pierre, she has bright green hair and has a little sunroom she uses as an escape.
Caroline!

Abigail, the daughter of Peirre and Caroline, has a weird habit where she will eat this mineral, if you give it to her as a gift. (You still can, its one of her liked gifts)
Quartz!
This empire is the one that Kent is at war fighting against during the players first year in the valley. And is supposedly a very violent empire.
The Gotoro Empire
In Harvey's 10 heart event (only available if he and the player are dating), he will take the player on a ride on this mode of transportation, ending the cutscene by kissing the player.
Hot Air Ballooooooooooooooooon
Our small island boy Leo, has said that he has a crush on this orphaned villager.
MY CHILD AND BEAUTIFUL BABY GIRL JAS!
This entity lives in the sewers and is known as friendly, despite their counterparts killing you in the mines. They are, the one option to ask to be your roommate.
OUR BOY KROBUS!

This not befriendable villager has a small hinted crush on Marnie, where he will say, "Marnie looks lovely today..."
Marlon!
This is the body of water that is sometimes brought up and is home to the fern islands where ginger island is. Characters can sometimes say "On this side of the-"
The Gem Sea
In Penny's two heart event, she is seen trying to help this villager, who then makes you choose if what you did was actually helpful.
George
When entering the witches hut, there are three statues. One of these, if given a prismatic shard, will sacrafice your children and turn them into this animal.
Doves!
You can not build hearts with him, but he is quite helpful. He is the museum curator and gives you gifts after certain numbers of donations. He wears a swanky blue hat!
Gunther!

All the marriage candidates have counterparts, but it isn't hinted that there is anything between them other than a close friendship. That isn't the case for this villager though, for if you are engaged or married and ask her to dance at the flower dance, she will say "But... But I wanted to dance with... Just kidding! Of course I'm dancing with you. I love you."
Abigail! (Also, she said “I heard you and Sebastian started dating... I didn't realize you guys had a thing...” If you and Sebastian started dating?!?!)
According to Harvey's plane coordiantes, if Stardew Valley was on our real earth, it would be in what country?
Russia! (and specifically a land locked part of it, which is how we know Stardew Valley is not actually on earth.)
In the Dwarf's one and only heart event, he is seen fighting with Krobus. They are discussing the long time war between their species. Then, this person comes down to stop them.
The Wizard!
On Ginger Island, there is the pirate cove which will occasionally be visited by a bunch of pirates. Two of these pirates talk to each other, and are a nod to these iconic video game siblings.
Mario and Luigi!