The games begins with instructing you to "Name the fallen human.", and if you chose "CHARA" (an abbreviation of "character") it's referred to as "The true name." It is eventually revealed at the True Pacifist route that Chara is not the player character but the first human to fall into the Underground. Chara also takes control of the player character throughout the Genocide route and appears in person at the end of the route. Chara will also possess the player character at the end of the True Pacifist route endings if the player has ever finished a Genocide route run beforehand.

Chara is similar to Frisk in appearance as they both have short brown hair with locks behind their ear, but instead, they have brown eyes, paler skin, rosy cheeks, a long-sleeved two-tone striped green and yellow scheme as opposed to purple and blue with a single stripe on their shirt instead of two. They wear brown shorts or brown pants, and brown shoes. They are androgynous in appearance as well.

They are also seen with hollow eyes with liquid coming out and a wide open smile that's black.

Although they canonically have brown eyes, most fanart depict them with red eyes instead. They are sometimes depicted with black pantyhose, black ankle socks/kneehighs, brown ankle boots, two-tone striped green and yellow sweater, a gold heart locket, and seen holding a knife in fanart instead. They are also sometimes depicted with chocolate as they are implied to like chocolate.

If they are depicted as male or female instead, use genderswap (otm) or genderswap (otf) respectively.

Their adoptive brother is Asriel Dreemurr.