¿ Bill Cipher ?

Bill Cipher is a magical creature, a powerful demon capable of entering a person's subconscious.
Appearance: A yellow triangular creature with a large eye in the center, resembling an All-seeing Eye. The character also has thin black arms and legs. Bill wears a black bow tie and a top hat on his head. During aggression, the Cipher turns red sharply, and the eye increases several times.
Before acquiring a physical body, Bill could appear in human dreams, as well as control the mind. Upon contact with the Cipher, a person falls into a trance, during which a contract is concluded. At the same time, the world becomes black and white, and Bill can influence it as he pleases.

Bill is a guy

Headdress: blue and white cap with the blue spruce symbol.
Hair: somewhat disheveled, brown, rather long, a tuft is visible from under the baseball cap.
Skin: relatively pale, nose slightly darker than the rest of the face.
Eyes: brown, like Mabel's, with noticeable bags under them.
Clothing: dark blue vest, reddish-orange T-shirt, gray shorts, white socks with red stripes, black sneakers. Sometimes he is seen with a green backpack.
Distinctive sign: a birthmark on his forehead in the shape of the constellation Ursa Major, which he hides under his bangs.

Dipper is a guy

He is 13 (soon 14)