Disabled Means Helpless

When some people meet a person with a disability, they automatically assume that the individual is totally incapable of looking after themselves, and treat them as such. Most egregiously, some people even assume that having one disability equals having every disability! These people are the ones who insist on SHOUTING AT THE BLIND, assuming they can't hear, either. These patronizing attitudes often create resentment on the part of people with disabilities.

In fiction, they have little problem telling the offender exactly that.

Learning this is not true is often the point of a Very Special Episode. Contrast this trope to the Handicapped Badass, who everyone can instantly tell is not to be messed with.

Anime & Manga

 * Sometimes it seems as though Nunnaly from Code Geass feels this way. She is the one with the disability (she can't walk or open her eyes), and prefers for the entire first season to have Lelouch take care of her, even though they're both teenagers (she gets better about this and finally starts acting on her own in season 2). In Episode 21 of R2, Lelouch says that Nunnally kept smiling because, disabled as she was, it was the only way she knew how to show her gratitude to him.
 * In the Kidou Tenshi Angelic Layer anime, this is why left her child  under the care of others.

Comedy

 * Ventriloquist Jeff Dunham in Arguing with Myself. In one of the bits he talks about doing a show and having a signer there for a group of deaf people. Hilarity Ensues. Politically incorrect, but hilarious.
 * The intro to Ricky Gervais Politics Stand-Up show includes him talking extremely patronizingly to a guy in a wheelchair. When the guy protests that just because he's in a wheelchair doesn't mean he's mentally disables, Gervais turns to the camera and says "so he's leg mental, but he's not head mental..."

Comic Strips

 * Cartoonist and artist John Callahan has a lot to say about this subject. One book title is Don't Worry He Won't Get Far on Foot and another is Will the Real John Callahan Please Stand Up.

Films -- Live-Action

 * Subverted horribly in the film, Blindness. The men of ward 3 prove not to be harmless, and end up being harmful instead. Their self-appointed leader has

Folklore

 * An urban legend tells a tale of a guy who has one of his car's tires deflated while in front of a lunatic asylum. While he changes the tire he puts the bolts on the rim, just as a car goes through, scattering them. The man is unable to find the bolts he needs, so one of the lunatic patients tells him to use one bolt from each other wheel. He does and is surprised that the lunatic had that good idea. The lunatic's response? "I'm crazy, not stupid."

Literature

 * Most adults treat Agnes Thatcher, who is deaf, this way in Is That You, Miss Blue? and some girls even set her up with a blind guy at a dance. She especially resents people writing notes to her since she's an expert lipreader, and will write "What?" in reply.
 * In The Baby Sitters Club spin-off series Little Sister, Karen's class gets a new girl named Addie who has cerebral palsy and so is confined to a wheelchair. Karen takes it upon herself to help Addie -- which means she does everything for her, despite both Addie and Ms. Colman telling her that Addie is perfectly capable to doing things for herself (such as sharpening her pencils). She doesn't listen, and both the readers and Addie get seriously ticked off.
 * Elizabeth Bathory's feelings of self-loathing in Count and Countess are a result of this mindset. (She suffers from severe epilepsy throughout the novel.) She later subverts it however, making her more of a Handicapped Badass.

Live-Action TV

 * On Degrassi High, Maya's friends neglect to invite her to a movie because the public buses don't have lifts and the theater they're going to doesn't have a wheelchair ramp. She finds out and tells them off for not even asking, when she has a van and knows many place that can accommodate her.
 * Clark went blind in one episode of Smallville, his parents thought that stepping out of his eyeline would be far enough away for him not to hear them talking about him.

Video Games

 * Illidan in Warcraft III seems to lampshade this trope: "I'm blind, not deaf!"

Visual Novels
On the other hand, Hisao tends to internalise this at times, and realising that this trope isn't true for Hanako is one of the main goals of her arc -- after she suffered a panic attack in class, he started thinking of her as someone helpless he needed to protect, instead of an equal romantic partner like Hanako wanted. In the good route, Hisao In the bad routes, he either, or
 * Cheerfully Averted Trope (possibly even defied) in Katawa Shoujo: Rin has no arms, but is very agile with her feet; Emi has no legs, but runs track using prosthesis; Shizune is deaf-mute, but serves as an effective and ruthless Student Council President (with a Translator Buddy). Indeed most of their real problems are only partially informed by their disabilities, for example Shizune is extremely extroverted and eager to interfere in other peoples lives because her inability to speak makes her isolated and easy to ignore, but also

Web Comics
"Monette: ... I don't know how Dahlia sat in that chair for ten years without killling someone.
 * In Something Positive Dahlia challenged Monette to sit in her wheelchair for one trip (while she can use a wheelchair as a walker). Later Monette remembers Dahlia's dad used to work at a helicopter factory.

Dahlia's mom: She did it with patience, friends and a father who helped her calculate the proper ramming speed in an electric wheelchair to correct other people's assumptions.

Monette: No chair-mounted gun turret? And I thought he was a real Texan."

Western Animation

 * In the Arthur episode "Prunella Sees the Light", Prunella invites her blind friend Marina over for a Henry Skreever sleepover. However, she worries that Marina may not see the decoration in her room or may get injured because she is blind. Marina doesn't like the special treatment Prunella is giving her, and Prunella learns to treat Marina just like any other friend, although we also see the tricks and methods that Marina uses in her own house, but here they are her methods and her choices.
 * An episode of Clifford the Big Red Dog has a three-legged dog. Clifford and T-Bone assume the dog needs a lot of help and Cleo believes the dog has, as she put it, "some kind of leg-losing disease" and if they came into contact with him, they too would get it. At the end of the episode, the dog calls them all out on this, explaining that while he appreciates their help, he can do things himself and assuring Cleo he is not at all ill as she thinks.
 * This is also why Toph's parents in Avatar: The Last Airbender kept her so sheltered that even her existence was a secret.
 * This was the villain's explicitly stated intention in one episode of Jackie Chan Adventures, when he kidnapped Uncle and cast a spell that rendered Jackie mute, Jade deaf and Tohru blind so they couldn't rescue him. Needless to say, they did anyway, and a lesson was learned by all.
 * Happens in an episode of Rocket Power. Reggie is in a snowboarding competition with another girl she recently befriended who happens to use a wheelchair. Reggie lets her win... and gets a What the Hell Hero from her dad and everyone else. The remainder of the episode is Reggie trying to figure out how to make it up to her new friend.

Real Life

 * Deaf actress Marlee Matlin once told about her experience with the "one disability = all disabilities" part of this trope when she was on an overnight flight. The flight attendant was passing out menus for dinner, and Matlin began signing what she wanted to her interpreter. The flight attendant saw her, immediately snatched the menu away, went back to her station, and returned, proudly handing Matlin a menu in Braille. Matlin facepalmed.