I've been using the MBTI quiz to build upon my characters' personalities and it's been pretty helpful so far, so I thought I'd share the tactic!
Here's a link to the website where you can take the quiz and find out more about each type: https://www.16personalities.com/free-personality-test
My characters:
Minnie: ENFP (Extroverted, Intuitive, Feeling, Prospecting)
Shares personality with MCU Peter Parker.
Sage: ISFJ (Introverted, Observant, Feeling, Judging)
Shares personality with Dr. Watson.
Ethan: ESTP (Extroverted, Observant, Thinking, Prospecting)
Shares personality with Samuel L. Jackson.
Reese: INTJ (Introverted, Intuitive, Thinking, Judging)
Shares personality with Gandalf the Grey.
I use the same site and agree; it has been very helpful for me too! A few test results that I thought were right-on:
Ewan Bailey: INFJ-A (Advocate)
Emma Greene: ESTP-A (Entrepreneur)
Malachi West: ENTP-A (Debater)
General Greene: ISFJ-T (Defender)
I tested this on four of my ocs and it's like- kindof scary accurate-
Jay: ENFP-T
Onyx: INTJ-T
Samuel: ESTP-T
Discord: ESTP-A
i already had mbti types so im gonna see how close i was after doing this test
Frog: [ENFJ] INFP-T, The Mediator
Dick: [ESTP] ESTP-A, The Entrepreneur
Juniper: [ISTJ] INTJ-A, The Architect
Shiloh: [E/ISTP] ESTP-T, The Entertainer
edit: I didn't do all of my OCs, since I didn't have the energy to take the test 6 times, but I finished it with my last two
Vanessa: [ENTP] ESTJ-A, The Executive (although i genuinely think she's more ENTJ-A)
Alex: [ENTJ] ESTP-A, The Entrepreneur
I have an ESFP-A character, which is funny because when I took the same test I got the exact opposite (INTJ-T- other tests say I'm INTP, though)
This was really fun! I feel like I got a lot of inspiration to further develop my character's personalities from this. But, I also got a bunch of interesting/unexpected results. For example:
The most accurate result I got for a character was Jacklyn, who ended up being an Executive (ESTJ-T). The least accurate result I got was for David, the smug, abusive asshole with zero empathy and a persona that radiates toxicity. He ended up being a Mediator (INFP-A), the personality characterized as being "Poetic, kind, and altruistic". lol if you say so
Speaking of Mediator characters not being accurate: Of the four Mediators I have, only one of them fits the "nice caring uwu" stereotypical personality. The others are 1). A woman with anger issues who killed her husband 2). A serial killer obsessed with fire and 3). Literally David.
The personality with the most characters in it was the Advocate (INFJ), with five characters: Romy, Jem, Ludka, Jules, and Remond. The only personalities with zero characters were the Commander (ENTJ), Consul (ESFJ), and Virtuoso (ISTP).
The character I most heavily relate to, Lucky, got Adventurer (ISFP-T), which is the exact same as my MBTI. Even down to the T/A. I lowkey feel like halfway through his test, I just started answering the questions as myself because of how similar the answers were to mine.