Kingdom Hearts
Sora, Donald, and Goofy followed the White Rabbit into the Bizarre Room. As soon as they enter, they see that the White Rabbit has shrunk and ran through a small door. Sora and his friends look at the door and wonder how the White Rabbit got so small. Much to their surprise, the Doorknob starts talking and tells them to try the bottle on the table, then goes back to sleep. Much later, Sora comes back to the room and defeats the Trickmaster. The Doorknob wakes up after the battle and yawns to reveal Wonderland's Keyhole, which is inside of his mouth. Afterward, the Doorknob goes back to sleep.
 Kingdom Hearts 358/2 Days
When Roxas first visits Wonderland and enters the Bizarre Room, he is originally trying to find the White Rabbit that ran past him, but finds the Doorknob instead. The Doorknob tells Roxas that the Rabbit drank from the bottle on the table. Roxas, being confused, asks the Doorknob about the White Rabbit and the door, but the Doorknob is fast asleep and won’t answer.
 Kingdom Hearts coded
While exploring the Bizarre Room, Data-Sora sees the Doorknob, who has been turned sideways due to the bugs. Data-Sora volunteers to eradicate the bugs afflicting the Doorknob, and after Data-Sora returns from the System Sector in question, he receives the "Doorknob" Inkling.
The Doorknob is, true to his name, a sentient, gold door handle. His escutcheon plate is shaped like an elongated trapezoid with a semi-circle bump on the bottom and a curly design on the top, giving the Doorknob the appearance of having a chin and hair, respectively. A gold screw on each bottom corner of the plate keeps the Doorknob attached to his door. He has close-set, beady yellow eyes and what seem to be black "eyebrows", though these may actually be engravings on the Doorknob's plate rather than hair. The Doorknob's prominent bulbous nose is actually the knob part of a doorknob, the part that is turned to open the door, something the Doorknob doesn't pretend to enjoy. His mouth is the keyhole part of a doorknob (as well as the Keyhole of Wonderland), though it is not fixed in place like it should be; the Doorknob has no problems moving his "lips" to talk.
Although the Doorknob appears in Kingdom Hearts Re:coded and has talk sprites, he is not listed in the Debug Reports.
The Doorknob is not particularly helpful, caring only about getting sleep. He is lazy, quite obviously, as a short cutscene is always played when approaching him that shows the Doorknob snoring. He does, however, offer some help, as he tells Sora that he is too big, and that he will need to drink the potion. He is also rather acerbic, as shown when Goofy offers a pleasurable "G'mornin" in Kingdom Hearts and he bluntly says, "Goodnight! I need a bit more sleep."
The Doorknob first appeared in Walt Disney's 1951 film Alice in Wonderland as a minor character. Like its game counterpart, he only had a few spoken lines near the beginning and the end. Interestingly enough, there is no Doorknob in the original Lewis Carroll novel.