Boards
Worst supporting character cliches
The silent, senile grandparent in a chair cared for by the protagonist to lazily illustrate a caring personality.
In a comedy - will periodically disrupt staid events by wandering in and doing something crazy
In a drama - will be mute and motionless
Will invariably emerge from decades of dementia/muteness near the climax of the film to whisper one insightful piece of advice.