Episodes with Amnesia

Amnesia is a deficit in memory caused by brain damage or disease, but it can also be caused temporarily by the use of various sedatives and hypnotic drugs. The memory can be either wholly or partially lost due to the extent of damage that was caused. There are two main types of amnesia: retrograde amnesia and anterograde amnesia. Retrograde amnesia is the inability to retrieve information that was acquired before a particular date, usually the date of an accident or operation. In some cases the memory loss can extend back decades, while in others the person may lose only a few months of memory.

From TVTropes: "Amnesia comes easy in fiction. It is also conveniently specific. A taste of Applied Phlebotinum, a particularly shocking traumatic event, or even a simple Tap on the Head will be sufficient to make your character forget all about who or what they are. In most cases, the character has simply lost their memories, no longer remembering their name, loved ones or where they came from. This is often the cause for a Quest for Identity."

Related TV Tropes

 * Easy Amnesia
 * Identity Amnesia
 * Tap on the Head
 * Amnesia Danger
 * Amnesiac Lover
 * Criminal Amnesiac
 * Amnesiac Hero