The user can generate acid and manipulate the corrosiveness, from having weak burning sensations to burning a big hole in even the strongest materials. User may be immune to acid.
May be limited on how much acid that can be produce.
Takes time to control due to the risk of the ability could accidentally destroy items the users didn't mean to destroy.
May affect one's personality.
Known Users
Magellan (One Piece); technically a poison-user, but one of his poisons behaves more like acid.
Terumī Mei/Fifth Mizukage (Naruto); can produce a kind of vapor that is corrosive
Lily (Code: Breaker)
Sesshomaru (InuYasha)
Gluttony, acidic saliva (FullMetal Alchemist)
Preta Ghoul (Black Cat)
Anarchist (Marvel); could sweat acid and fire acid blasts from his hands.
Man-Thing (Marvel); uncertain whether the acidic burn caused by his powers is mystical or biochemical. Stated in some comics to be "sulfuric acid" though it has been shown to burn even those with superhuman durability.
David North/Agent Zero (Marvel)
Lehvak (BIONICLE)
Artilas (Geneforge series)
Roamers (Geneforge Series)
The Freaks (Crackdown 2)
Spitter (Left 4 Dead 2)
Marlboro (Final Fantasy); debatable, but Marlboros produce various types of ill effects, one of which could be considered a corrosive acid.
Reptile (Mortal Kombat)
Hazmat (Marvel Nemesis: Rise of the Imperfects)
Viron.Volkov (Storm of the Imperial Sanctum)
Subterran.Unix (Storm of the Imperial Sanctum)
Joseph Bertrand III (Infamous 2)
The Xenomorphs (Aliens); some variants can spit acidic saliva, while all variants blood highly acidic blood.
Lehvak (BIONICLE)
The Bahrag queens (BIONICLE)
Goop (Ben 10: Alien Force)
Acid Breath (Ben 10)
Scabbar Demons (Charmed)
Karen Young (Charmed); was used by power brokers to hold this power.
Paige Matthews (Charmed); was stored with this power by power brokers.
Guy with Acid Spit (Sky High)
Hocker (Lilo & Stitch)
Quarry (Teenage Mutant Ninja Turtles)
Angel Salvadore (Marvel Comics)
Pokemon who can learn "Acid" (Pokemon)
Melona (Queen's Blade)
SCP-811 (SCP Foundation)
Gear REX (Metal Gear Solid: Peace Walker)
Burak/Gabo Alvarez (Kidlat - Filipino Superhero TV Series)
Gallery
Magellan (One Piece) can create a poison that has acidic properties.
Mei Terumi (Naruto) can generate a corrosive mist.
Sesshomaru's (InuYasha) claws release deadly acidic poison which can melt flesh and virtually anything else very quickly and he can also spray the poison from his claws.
Lily (Code: Breaker) can produce various acids and poison.
The Lehvak (BIONICLE) firing a jet of acid.
Preta Ghoul (Black Cat) can release corrosive acid from his body.
Hazmat (Marvel Nemesis: Rise of the Imperfects)
Gear REX (Metal Gear Solid: Peace Walker) can fire acid from its tail.