Terry

He is a mystic who helps lost souls get over their obsessions.
In the movie, he tells Joe that he was a lost soul once due to his small obsession with Tetris.
Moonwind considers sign-twirling to be art.
Unlike Joe's soul, Moonwind's mustache appears on his.
According to the Target-exclusive gallery book that comes with the 4K Ultra HD Blu-Ray, & the Pixar 2023 one day at a time calendar, his actual name is Engelbert Humphrey Ruffleshire.

Lost Souls wander in The Astral Plane while their Earthly selves struggle to break free of obsession. “Some people get caught up in something that isn't necessarily bad—cooking, video games, art,” says director Pete Docter. “But if you do it to the exclusion of everything else in life, you might become a lost soul.”

A Lost Soul forms when someone is obsessed with something that disconnects with life. As shown with 22, a Lost Soul will change color and their appearance will gradually warp.
As demonstrated by 22, a Lost Soul can consume someone that sends them into a pocket dimension of the Lost Soul's inner turmoil. As experienced through Joe in 22, the Lost Soul's inner turmoil takes the physical manifestation that represents their insecurities and obsessions. 22's inner turmoil took the form of former mentors and Joe Gardner himself that declares her a lost cause and accuse her of having no purpose.

The Astral Plane is a plane of existence where every soul and lost soul inhabit when they are "in the zone", featured as a place adjacent to the You Seminar where lost souls are rescued from their uninspiring, stressful lives by Moonwind and his fellows.

The Great Beyond is a natural place for deceased souls who keep what made them "You" in their life. It appears as a cluster of light surrounded by a dark void.
After a soul's time on Earth is up, they jump down to a giant hole that takes said soul away from their body and mortal life and into the afterlife. They end up on a trail that goes up to the cluster of light.
A soul that is carried by the trail becomes into a blue sphere, and then a white orb, as they get closer to the Great Beyond, then starts to float into the "cluster". Many such souls who are brought by the trail seem aloof, or even excited, to reach the "cluster". Once they get close enough, they make a buzzing sound. Joe thinks that the souls who reach the "cluster" were being annihilated, frightening him into trying to run back.

Whenever the souls enter The Great Beyond, they briefly produce a trio of colors, yellow, cyan and magenta. That could be a reference to the subtractive CMY color model, a color model often used in printers.
The "trail" that leads the souls to The Great Beyond heavily resembles lines from the neck of a guitar (or other similar instruments), or a conveyor belt.
The movie's developers intentionally left the Great Beyond ambiguous because it represents that every person has a different interpretation of the afterlife.

The Great Before is a cosmic plane where young souls get their quirks, interests and personalities, all this so they can be ready for life on earth.
The entire place is operated by the abstract souls knowns as Jerrys, whose job is to assign the traits of every soul through the Personality Pavilions (some of the well-known pavilions include Insecure, Excitable, Aloof, Self-Absorbed, Mischievous, Anxious, Clingy, Funny, Empathetic, and Agressive).
Whenever the souls enter The Great Beyond, they briefly produce a trio of colors, yellow, cyan and magenta. That could be a reference to the subtractive CMY color model, a color model often used in printers.
After they get their personality all that is left to complete is their spark, this job is made by the mentors (the souls of deceased people who already had a life), so they help them to get inspired by anything from earth (example, food, music, their own inspiring moments in life etc)

You Seminar - The You Seminar is a place for young souls to be taught by the Jerrys.
Hall of You - A place mentors bring their unborn soul partners to show them their life to try to find their spark. There is a hand scanner that can show other people's memories.
Hall of Everything - A place mentors bring their unborn soul partners to show them all the possibilities of what to do on Earth so they can get inspired and find their spark.
Earth Portal - A circular portal where prepared souls go to Earth.

Likes:
Jazz music, living on Earth, his family, life, pizza, Binaca breath spray, cheap cologne, playing the piano, 22, pecan pie, the beach. Dislikes:
Dying, 22's cynicism, jazz music (formerly), cats (formerly), the word "jazzing" (formerly), his mother not supporting him, going to The Great Beyond.

He wears a grey fedora, a black sweater, brown pants, and red shoes.
As a soul, his nose is not featured, but his glasses and fedora are now part of him.

Joe is a passionate, driven, and talented jazz pianist whose life is defined by a singular, obsessive pursuit of musical success. He is always supportive and loves to bring out the best of people. Despite this, Joe can be a little stubborn, selfish, and impatient, especially when his dream as a jazz musician is involved. Upon realizing his dream of playing with Dorothea in a real jazz band, he feels it was not as rewarding as he thought it would be.

Joe Gardner is a middle school band teacher who has long dreamed of performing jazz music onstage and finally gets a chance after impressing two other jazz musicians during an opening act at the Half Note Club. As he was celebrating his new gig, he accidentally fell down a manhole. This put him in a coma, a state where he is neither alive nor dead, thus sending his soul to the Great Beyond and, later, escaping to the The Great Before (both being places between the Earth and the Great Beyond). There, he meets a soul with a dim view of life named 22, who he finds himself mentoring. Now with 22's help, he must find his way back to his body and thus wake up from the coma, before time runs out and he fully dies.

Likes:
Earth, dancing, mimicking Joe, life, pizza, music, lollipops, food, shushing people, having a conversation with others, annoying others (formerly).
Dislikes:
Earth (formerly), being told she has no purpose, being yelled at, failing, music (formerly).

Physical appearance:
22's body is shaped like the other souls in The Great Before (besides Joe), like a light bulb. She is light aqua with faded pink cheeks, purple eyes and eyebrows, a buck tooth in her mouth, a tuft of hair on the back of her head, and no legs. However, she is able to form legs whenever she wants, as seen when dancing and running. Whenever 22 shapeshifts into someone, she still has her purple eyes.

22 sounds like a "middle-aged white lady" because, according to her, it is the most annoying voice she could think of, adding that she could sound like whoever she wants.

22 is a soul with a snarky and cynical attitude. She is not interested in having a life on Earth and would rather stay at the Great Before due to believing life on Earth to not be that great. 22 would even push her mentors away whenever they try to help her in finding her "spark" to complete her Earth badge. 22 also speaks in the voice of a "middle-aged white lady" just to annoy people and to keep them away from her.

22 (the 22nd soul ever created) is a precocious soul who has spent hundreds of years at The You Seminar, where new souls must meet several requirements before going to Earth. Like every soul before her, 22 has been through the Personality Pavilions, which explains her endearing sarcasm, quick wit and occasional moodiness. She’s met every requirement to go to Earth—except one. But no matter how many visits she makes to the Hall of Everything, no matter how many esteemed luminaries have mentored her, she can’t find the spark she needs to fulfill her requirements and make her way to Earth. That’s fine with 22.

Likes:
Helping the New Souls
Joe Gardner's mentorship
Dislikes:
22's obstinacy
Terry's stubbornness

Jerries are a manifestation of dynamic energies, appearing in a comprehensible form, albeit abstract. The Jerries counsel and guide new souls and enlist mentors from the Great Beyond to be paired with soul. They interact with newborn and deceased souls, however not those currently living on earth.

Jerry can change their forms fluidly and constantly. They usually appear as two-dimensional abstract humanoids in shades of translucent purple. They can grow limbs and change size and shape constantly.

Because they are transcendent beings, they possess different abilities that souls don't have (except for shapeshifting).

They can shape-shift and change their form at their will to any possible situation (hiding from people, carrying souls, etc).
They also can open portals to almost every part of the universe (Earth, The Great Beyond, The Great Before, etc.), however it is unknown if they can go across the Great Beyond portal and come back.

Jerry is the entirety of the universe condensed into a form humans can comprehend. Jerry has as many forms as it needs or wishes for managing every soul in existence before they are sent to Earth. They have a counterpart, Terry, who seems to be in charge of souls after death.
Most of the Jerrys are shown to be optimistic and helpful, but most importantly kind to every soul no matter what, this was shown when they try to help a lost 22, and when they give Joe Gardner another chance to live.
Even though they work in the area of inspiration, they rarely get inspired, this happens because they probably know everything that exists in the universe and that being surprised can be difficult.

Terry is a very hard-working and perfectionist accountant. She isn't really evil, the only reason why she pursues Joe is because she notices that her soul count is off, and intended to correct it, thus showing that she is only trying to do her job.

Terry's job is to count souls that go from the Great Before to the Great Beyond. However, she hits a snag when newcomer Joe Gardner abandons the pathway in order to try and make it back to Earth. Obsessed with her quota, Terry convinces the Jerries to let her venture outside her jurisdiction to the Land of the Living to try and find Joe and bring him back. She eventually manages to find Joe and 22, and is awarded (by request) a trophy for her duties. However, the sudden calamitous arrival of the lost soul of 22 (with Joe in close pursuit) prompts Jerry to revoke the trophy. Later in the film, Terry is seen easily distracted by a Jerry, who quickly resets the accounting in order to avoid a repeat of the same affair.

Occupation: Accountant
Powers and abilities: Shapeshifting
Terry is an accountant whose job is to count souls who go to The Great Beyond.

Terry is a peculiar extension of the team of The Great Before, charged with the singular duty of keeping track of the entrants to The Great Beyond. Each Jerry does their best to tolerate Terry, whose obsession with The Count can be burdensome—especially when it's off. So, when Joe Gardner takes a detour to The Great Before, Terry is determined to make things right.

Terry is first seen counting the souls going into the Great Beyond. She subsequently notices, and tells one of the Jerries, that the count is off. This frustrates her, and she subsequently heads to the You Seminar to inform all the Jerries about the count being off, as 151,000 souls enter the Great Beyond each day, however it is off by one number. She then heads to the records to look for who caused the count to be off.

Terry is somewhat of a perfectionist, as she is always trying to make sure that the count stays perfect.

Very much like AUTO, Terry is an antagonist who is just trying to do her job, except she never resorts to using violence.

Terry is a female. Terry has the appearance of an elderly lady with a hair bun.

When Terry appears, playing: Trent Reznor and Atticus Ross - Terry Time.
She is the same being as Jerries.

Souls cheating death unjustly, the soul count going off, not getting recognized for a job well done

Trophies, keeping track of souls, her job