The Prisoner

The Prisoner, sometimes referred to as the P.O.W. Toad, is an anomalous entity present in some personalized copies of Super Mario 64. While there are varying reports on the behavior of the Prisoner Toad, most say the toad either asks to freed from a cage, or will steal important items and run off causing a chase.

Appearance
Witnesses described the Prisoner as being taller than all other toads in the game and wearing a cartoonish black and white jail jumpsuit, however another report mentioned he had a really threatening face, with one eye being gray.

Behavior
Usually they will either be standing in the open or hidden in a cage. If they are in a cage they will ask to be freed and will require you to find a key somewhere in the level. If they are standing in the open, they will often steal important items that the player needs in the level such as red coins or stars.

Report #1
(An example of The Prisoner stealing important items from 2011 by a man from Kent, Ohio)

“I was running around Cool, Cool mountain to collect the 8 red coins star. I went to grab the last red coin but in it's place was a toad I had never seen before. It looked like it had a prisoner suit on and it was taller than the other Mario 64 toads. Assuming I had encountered some type of glitch I decided to talk to the fellow. It said something like "I'm the best thief this side of town! You'll never catch me!". The toad then ran off with the red coin in his hands. It took some tricky maneuvers to catch up the guy, but after awhile I was able to stop the rouge toad. I laughed for a good bit at the toad’s defeat and finally completed the mission.”

Report #2
(An conversation about The Prisoner from 2018 on 4Chan)

"Hey weird question, but has anyone know where the key to save a toad in Shifting Sand Land?"

"Nice Troll."

"It's not a troll, I've been looking for walkthroughs of Mario 64 and can't seem to find anything on it."

"Ok, I'll humor you. What does it look like?"

"Well it's kind of tall for a toad, and it's in a cage. It's wearing a prisoner outfit and I think it's got a gray eye of some sort."

"Are you playing a hack?"

"No this is on console."

"No clue then."

Theorizing
As not many sightings of The Prisoner have been reported, it's unclear why the Personalization AI places this toad in certain copies of the game. However some have theorized that the players witnessing the toad may have guilt fore stealing something in the past, but this is just speculation.