The Player Character, he used to visit the farm during the summer as a child. His grandfather (the player character from the original SNES Harvest Moon) dies just prior to the beginning of the game. He decides to move to Flower Bud Village and work grandpa's old farm.
Black Bead Eyes: Most artwork for this game have Pete with this, though artwork from the previous game had his grandfather with blue eyes and artwork from most games prior have him with Brown Eyes.
Call to Agriculture: In contrast to his business suit-wearing father, he returns to grandpa's place to run the farm.
Fan Nickname: That his canonical name is Pete is an extremely little known fact since it's barely mentioned anywhere and doesn't pop up as the default name when you begin the game. He's called Jack by pretty much the whole of Harvest Moon fandom, to the point that many are surprised to learn it's not his canon name.
Heroic Mime: Though you can dictate his response to questions a few times.
Nice Hat: Perhaps his single most identifying trait is his backwards baseball cap that he wears in most of his incarnations. This was back in the '90s when wearing your baseball cap backwards was the single coolest thing you could do.
Flower Bud Village's five eligible young women. The majority of the social events involve them (either interacting with you, with the rival bachelors, or with each other), making them arguably the most important characters in the game. Each also has a sequence of "relationship events" showing your growing affection for each other — you'll visit them at home when they get sick, find them stranded somewhere after they've twisted their ankle, recall a shared childhood memory, and share a unique special moment together. All five girls have all of these events, but they all play out a little differently.
Ann lives and works at the Green Ranch with her father and Gray, her brother. Rick from the tool shop is her cousin. Unsurprisingly, she's a big animal lover; if you let any of your animals die, she'll like you a lot less.
Expy: Of Ann from the original game, though given a new character design and changed from an inventor to farm girl.
Domestic Abuser: Believe it or not, this sweet, animal-loving girl shows shades of this if she marries Cliff. He's even depicted with a black eye in one sprite.
Identical Grandchild: Not to the extent of other examples, but she looks quite a lot like Ann from the first game and even shares her name.
Housewife: All the girls can end up as one, but Elli fits the stereotype best.
Karen lives at the vineyard with her father, Gotz, her mother, Sasha, and Kai, a vineyard worker. She works there during the day, but also works part time at the bar in the evenings (making her the only bachelorette it's possible to find at night).
Hollywood Genetics: She has blond bangs presumably from Eve, who is implied to be her grandmother. Incidentally, the same blonde bangs link her to Cliff as possible cousins.
Lost Forever: If you don't make friends with her, she'll eventually leave Flower Bud Village for the big city.
Maria is the Mayor's daughter, and works at the library. Initially the shyest and least confident of the eligible girls, she's actually the easiest to woo (conversations and gifts actually boost her affection faster than it does other girls).
The male residents of Flower Bud Village who compete with you for the girls' affections. They're typically not much of a threat to your love life, but if you make friends with them, you can see events where they woo their girl of choice.
A wanderer who shows up in Flower Bud Village during the first Spring, and lives on Moon Mountain thereafter. His girl of choice is Ann. Karen turns out to be his cousin (Eve, from the original Harvest Moon, is their mutual grandmother).
Lost Forever: Cliff will wander off again just like he wandered there in the first place unless you make friends with him.
Lives and works in the bakery with Elli, who is also his girl of choice. A bit older than the rest of the bachelors, he can occasionally be found at the bar contemplating his "no longer young, but not yet middle aged" status.
Wife Husbandry: The fact that he already lives with Elli and is significantly older than her can lead one to believe that he's a father figure for her, given her parents are completely unmentioned. Then when you get to know him, he turns out to be interested in her... It's not uncommon for players who don't really get into Elli's story to think Jeff is just flat-out Elli's father and Ellen's son. Comes as quite a shock if you decide to befriend them later and all of a sudden they're hooking up.
A worker at the vineyard, which is also conveniently where his love interest, Karen, lives. He's not from Flower Bud Village, and is somewhat conflicted about living his life in the country as opposed to the exciting big city.
Lost Forever: If you don't make friends with him and Karen leaves, Kai will eventually leave as well.
The village mailman, Harris doesn't actually seem to have a house, but can be found wandering around the village delivering mail. The object of his affection is Maria.
Love Hurts: If you chat with him at the bar, Harris will reveal that his growing relationship with Maria is actually causing him more distress as it gets deeper, because he grows ever more afraid of rejection.
He works on the Green Ranch with his father and Ann, his sister. Gray's girl of choice is Popuri. His preferred method of communication is a mix of Visible Silence and blunt questions.
Aloof Big Brother: While not evil by any means, he's among the least friendly people in the game, and clearly doesn't approve of your attempts to woo Ann (if you're making any). See also The Quiet One and The Stoic.
Not Good with People: He's a good ranch hand and used to be an excellent rider, but Ann quite accurately describes him as "a social disaster".
Sugar and Ice Personality: Gruff, stoic Gray going after pink and frilly Popuri is adorable. At one point he plants flowers at the ranch because he knows she likes them!
The family members of the lovely bachelorettes listed above. As supporting characters to the love interests, they tend to end up sharing the spotlight, at least to some extent.
Ranch Owner: Father to both Ann and Gray, he owns the Green Ranch. You can buy livestock and related supplies from him. His name is either Doug or Hall depending on your source.
Ellen: One of the eligible bachlorettes from the original game, now an elderly woman living with her granddaughter Elli in the bakery. She dies at some point during the game, providing the single biggest Drama Bomb of the game. As she does not refer to you as her grandson, she is the only original bachelorette who was explicitly not the canon love interest... though all of the other four are also strongly implied not to be, either, which results in some major Fridge Logic. Who was your grandmother anyway?
Gotz: Owner of the vineyard, and Karen's father. Unpleasant to deal with, and implied to be an alcoholic.
The Mayor's Wife: The mayor's wife. Maria's mother. Spends most of her time in her family's Big Fancy House, but can sometimes be spotting doing errands around town. Usually takes an active role in festivals, supporting her husband.
Basil: A botanist and Popuri's father. He leaves Flower Bud Village every Fall and returns every Spring, spending the time in distant places looking for plants to bring back home and sell. In the Mineral Town games he is turned into Mary's father. In Magical Melody he is turned into a younger marriage candidate.
Lillia: The village's "florist", meaning she sells seeds for crops, grass, and flowers. Basil's wife and Popuri's mother. Presumably the daughter of Nina from the original Harvest Moon; this is never explicitly mentioned, but her family line is the only one with pink hair.
Naturally, Flower Bud Village has many residents not involved in your romantic aspirations (though, admittedly, they tend to receive less focus).
Potion Shop Dealer: An older Asian man who runs a small store making medicinal drinks of various sorts.
Kent and Stu: The Potion Shop Dealer's grandchildren, who live with him. Their parents are dead, but we never hear the story behind that. They go to school (at the church) and wander around town during their time off. Kent is the older brother, and Stu the younger; Stu introduces himself as being seven years old the first time you talk to him. The two are rarely, if ever, seen separately.
The Midwife: An elderly woman who delivers the villages' babies. Sits around in her house the rest of the time. She was good friends with the player's grandfather. She is Zack's mother and May's grandmother.
Zack: Identified only as "the guy who ships your crops" in HM64, but his Expys in other games are named Zack. Shows up at your farm every day to take everything in your shipping bins (and pay you for them, naturally), and occasionally appears in the bar at night. May's father, and the midwife's son, though he is rarely seen with either of them. (Father and daughter appear together only once per year, at the Spirit Festival.)
May: A little girl that lives in the village. Her mother is dead and her father is Zack, so she seems to be raised primarily by her grandmother, the Midwife. Goes to school and wanders around similarly to (but separately from) Kent and Stu.
Saibara: The village artisan, a somewhat grumpy old man. His shop acts like a sundry goods store, offering a handful of things (like a vase to decorate your house, or an ocarina that can be used during a festival) that don't fit elsewhere. Never seen outside of his shop.
Priest: The pastor of the local church, who also teaches the village children on weekdays.
Duke: A distinguished gentleman who runs the bar in the evenings. Employs Karen part-time. Gives the player the last remaining bottle of the vineyard's prized "Door to Heaven" wine when befriended. Is seen outside the bar only once: at Karen's wedding (either to the player character, or to Kai).
Not every character in the game lives in town or the surrounding farms. These are the characters that live on Mount Moon (or Moon Mountain, the game is inconsistent about it).
Mountain Carpenters: A trio of handymen who live in a cabin in the mountains. One is an older man, the boss, while the other two are nigh-identical young men who work for him. They'll build additions to your house when you can afford them, and a few times ask for your help with part-time jobs.
Harvest Sprites: Three literally identical Nature Spirits that look more like Santa's elves than anything else. They speak Pig Latin at first, but gradually switch to "your language" as you befriend them. They live in a cave on Moon Mountain, and will sometimes feed your animals if you're unable to (sick or stuck inside due to typhoon) if you're friends with them.
Kappa: A kappa (of the friendly, gentle type) living in the pond on Moon Mountain. He only appears if you toss a fish into the pond, but he'll at least let you know how much he appreciates the offering.
Harvest Goddess: Another Nature Spirit, who takes the form of an elegant older woman. Can be spoken to by tossing an offering into the Harvest Goddess' Spring in Mount Moon, and will grant you small favors in exchange for the chat.
Restaurant Owner: An elderly man living in the small restaurant on the peak of Mount Moon with his wife. Was cut off from the village after the bridge connecting them was destroyed, but the player can find an alternate route up or wait until the bridge is rebuilt to visit.
Restaurant Owner's Wife: A kindly old woman living on the summit of Mount Moon with her husband. Completely and utterly senile.
A handful of characters don't actually live anywhere nearby, appearing only for specific events and then leaving again.
Gourmet: A connoisseur of all things fine food, he shows up at relevant festivals to act as a judge. Gonk as hell, he looks like a giant egg wearing a purple suit. Tends to Say It with Hearts.
Photographer: Shows up when there's a picture to be taken for your album, and then disappears again. Sometimes you won't even see him, you just get the picture in the mail the next day. Particularly creepy when the event in question is a romantic moment with your girl.
Tourists: A handful of people who show up for certain events. A trio of schoolgirls that attend races and fireworks, and a few different groups who will appear at your farm if you accomplish certain things (such as winning the horse race or cow festival, growing a large enough pasture, or having a large amount of flowers blooming simultaneously).