A while ago, I have read Vincent Baker's blog post "Things on Character Sheets", where he makes a convincing argument that things most pen-and-paper role-playing games (including, by extension, his own) put on their character sheets, in fact, have very little to do with those characters' character. This has inspired me to develop an alternative, system-agnostic character sheet that focuses on who the character is, rather than what they can do, inspired by (and liberally borrowing ideas from) several indie RPGs. This was back in 2017, and I have since used it to help create several characters for my self and for my friends, but this is the first time I share the document with the public.
When (Not) to Use It
First off, if you are playing a fiction-first RPG (read: anything based on playbooks or associated with The Forge), you probably don't need my sheet. These RPGs already include most of what on it, trimming it down to the things are actually necessary for the stories they facilitate. Instead, my character sheet is intended for use in conjunction with the regular character sheet of whatever systems-heavy role-playing system is powering your campaign (like D&D, Vampire, etc.).
Secondly, don't bother with my sheet for one-shots (unless you are the GM pregenerating characters for a con game). In my experience, it's best to fill it out as a group during session zero of a longer campaign, in which player characters will have the time to evolve and to grow. Of course, I am not telling you how to have fun, but in my experience, coming up with an interesting, well-rounded character for a one-shot is an unnecessary overkill.
How to Use It
Character name and player name are just there for easier bookkeeping. Also, in my experience, most players have trouble coming up with cool character names, so don't feel bad for leaving that field for last.
High concept is stolen wholesale from Numenera and is a combination of a primary archetype (in a D&D-likes, it is the race+class combo; in genre-based games, it's a genre archetype, etc.) and a secondary descriptor or twist that distinguishes this character from other examples of that archetype. For instance, you can be a "human sorceress whose grandmother is a golden dragon" or an "anthropomorphic mouse who wants to be a musketeer". The idea of high concept is that other players go "Oooh, I wanna adventure with that guy/girl!" when they hear it.
Trouble, meanwhile, is stolen from Fate Core and represents an overarching problem plaguing the character's life, something to be resolved in the long term. It can be a personal struggle (like a curse, an incurable disease, substance abuse, etc.) or a bad relationship (with another person, an organization, etc.). By inventing a trouble for their character, a player decides what will definitely spur said character to action, giving the GM narrative resources to make the campaign more personal for them.
The quirk is a purely cosmetic trait that makes the character stand out from the crowd, the idea of which comes from Full Throttle fan RPG, of all places. A quirk can be the way they dress, a fully-functional prosthetic limb, or a scent of sandalwood that follows them wherever they go. The remaining three appearance & behavior traits flesh out how the character looks to an outside observer. The observation that nobody remembers more than three details about their character's looks comes from octaNe, by the way.
The history section is based on the assumption that the player character is a seasoned adventurer but originally had a more sedentary lifestyle. The background concerns said sedentary lifestyle, giving the character an additional dimension beyond "I kill stuff for gold". The turning point is the classic call to adventure, superhero origin, etc. Both of these points were directly inspired by the original Mass Effect's options for Commander Shepard's background. The last point, the kicker, is directly lifted from Sorcerer (down to the specific term), and is an event (emergency, opportunity, mystery, etc.) just before the start of the current adventure that provided the character with a personal stake in its outcome. Often related to the trouble in some way.
The relationships section is a combination of Apocalypse World's Hx mechanics and Blades in the Dark's friend-and-rival choices. The former connects the characters among each other, the latter anchors them in the GM's game world. Like in Apocalypse World, it is not required to have an existing relationship with or opinion of every other player character, but the relationship web must become a connected graph at the end. The non-player character relationships are limited to just two in order to both put due focus on the main cast, and to avoid overloading the campaign with supporting NPCs before it even starts.
Finally, the notes section is just there to jug down incomplete ideas, doodles, and anything else that doesn't fit in other sections.