Hoteyes (Fairy Tail) using Heaven's Eyes to find Midnight.
See through solid matter
The power to see through solid objects or people. Variation of Enhanced Vision
The user’s eyes emit a ray frequency that enables for a transparency effect (i.e. x-ray) to visually penetrate solid objects or even see within objects. Can be used medical motives, to perceive cancers, tumors, or even blackened lungs the basic human eye perception cannot normally perceive. The skill of perceiving a specific location (i.e. artery) is given by partial reflection of the ray from each specific surface surveyed. The direction of incoming light allows for a positioned focus on the depth of a viewing surface.
See through solid objects.
See through organic matter, allowing them to survey a person who could be injured or sick.
Like actual x-rays, Superman's X-Ray vision can't penetrate the dense metal Lead. Bizarro, who has the reverse powers of Superman, is only able to see through Lead with his power but not through anything else.
Looking through more than one wall may be impossible or confusing.
There may be objects/material that cannot be observed by X-Ray Vision.
May not be able to see through certain substances.
Lynceus (Greek Mythology)
Peter Quinn (Marvel)
Kara Zor-El/Supergirl (DC)
Bizarro (DC) Has the reverse of Superman's powers (i.e. Lead-only vision)
Nurse Spex (Sky High)
Blossom (Powerpuff Girls)
Bubbles (Powerpuff Girls)
Buttercup (Powerpuff Girls)
Falcon's Eye users (Xiaolin Showdown)
Kat (Kid vs Kat)
Toa Kopaka (Bionicle); via Akaku
Toa Whenua (BIonicle); via Ruru
Hyuga Clan (Naruto) via Byakugan
Byakugan users (Naruto)
Viola (One Piece)
Astro Boy (Astro Boy)
Hoteye (Fairy Tail)
Samus Aran (Metroid); via X-Ray Scope or X-Ray Visor
Ultra Boy (DC Comics)
Adam Jenson (Deus Ex: Human Revolution)
Captain Hero (Drawn Together )
Poli Truper (Supertorpe)
Witches, werewolves, shape-shifters, faes, warlocks, hybrids, vampires and chameleons (Shadow Falls); Limited to only seeing the brain pattern of another creature.
Wendy (Chica Vampiro)
Superman inspects Lois Lane for internal damage.
Clark Kent sees his friend clearer than ever (Smallville/DC)
School nurse with a useful talent...(click to animate)
Kurt Pastorius alias Refrax (Marvel) can fire thermal energy from his eyes as well as use X-ray vision.
Jess (Misfits) is shown seeing Rudy talking to someone locked in a freezer through a solid wall.