Mac was one of my original 2 starters and he's still on my island. Nan and Dotty came very soon afterwards though and they're both still residents on my island too.
Sherb was the first villager to move to my island not counting the first two, and has been there ever since. I think I got him 2 days after the release of the game.
Erik the Moose (Deer). Erik was my second lazy. My first lazy was some chicken that had one of the starting homes. When he left, I needed a lazy to feel the void and so I found Erik while island hopping. I never had him in NL so having him in NH was a nice surprise. I haven't let him go yet because he's just too cute.
I still have my original smug camper, Zell. Butch was my 10th villager, and I kept him for a really long time too. I'm still kinda bummed at myself for letting him finally leave.
Mine would be Reneigh. She was one of my two starters. Ive almost gotten rid of her. But since she was a new character that doesn’t have an amiibo yet (soon though) I haven’t gotten rid of her. But with the new DLC, I will finally be able to give her house a make over, so I’m going to keep her a little longer.
The only two starters I have still are Sydney and Antonio. Antonio has been on my island 2 days longer than Sydney. I always used to think Antonio was ugly in previous games and I don’t think I ever interacted with Sydney before New Horizons, but now they’re my favorite villagers! I always thought I wasn’t a huge Jock fan until I met Antonio. And Sydney has a bunch of items I gifted her that she looks so cute in.
My longest staying islander is Buck he was one of my day ones and is still here to this day. I don't want him to leave either just yet he is a sweet friendly horse.
Molly was the longest villager I used to have on my old island before it was deleted. Luckily I have her amiibo card so I was able to invite her to my new main island Destiny.
Pango, she was the first villager to move onto my island way back in march 2020- got too attached to her to let her leave.
Only other one of my first 10 villagers still around is Biff who was 9th, I think?
My last reset was in the last few days of November 2020, so about 11 months ago. I am done with resetting my island.
Olive
After inviting my first smug camper to stay, the first villager I met on a Mystery Island was Olive, my favorite Animal Crossing character with Pate. Anyhow! She moved in on December 10, 2020. So that makes her #7 on my island. She is a permanent fixture of my island, and I am glad she is still with me.
Tank! He was one of my starters and he's been with me ever since. Not sure if I'll ever let him go, he's not actually asked to move at any point yet. Originally I was fine with letting him go but I've grown somewhat attached to him over the 9 months I've had this island.
Mine is Pierce. He wasn't an original 2 starter, but he was an original five starter. I got him while island hopping cause I used to be best friends with him back in Wild World before I reset my town a bajillion times. Since then he's stayed on my island throu 3 theme changes. He's never leaving, not even to go to my second island so he can have his actual home rather than his starter home, then come back to my main island. I think him having his starter home will say alot about him when others see it in a dream plus I'm not a fan of his actual home cough cough cough
I restarted my day 1 island not long after the initial release, and Dom was one of my starters on my new island! He's been with me for over a year now, I don't recall exactly how long it's been, but he's not going anywhere. I adore him!