This trope is a fun one that is often used to introduce (or re-introduce) extremely dangerous antagonists who, due to their abilities, cannot be held like a normal prisoner.  It doesn’t always have to be a ‘bad guy’ seen under these circumstances, though, but either way, more often than not the prisoner launches a very daring escape to go wreak havoc on the outside world. 

Examples: 

Magneto from the X-Men is shown in his elaborate, specially constructed plastic prison in X-Men and X2 (1999 and 2003). He must not be able to use metal manipulation to escape, but in the 2nd installment, his partner Mystique helps spring him out in a very creative way. 

Dr. Hannibal Lecter in The Silence of the Lambs (1991) is played by Anthony Hopkins as an incredibly intelligent psychopathic murderer who is kept alongside other particularly dangerous prisoners. He may not have super powers per se, but he’s incredibly clever and preternaturally strong and capable. When they need to transport him, he’s seen fitted on a dolly with a straitjacket and a mask. He’s able to escape later, leaving behind incredibly gruesome murders to do so. 

Tai Lung - Kung Fu Panda (2008) Voiced by Ian McShane, Tai Lung is the former Star pupil and adopted son of Master Shifu. But refused the Dragon Scroll, he rebels until he’s defeated by the powerful Master Oogway. He is kept in a heavily armed dungeon under chains and weighty handicaps. All he needs to not only initiate his escape is a goose feather.

Boris the Animal - MIB 3 (2012) Jermaine Clement plays this evil, deadly alien creature first seen breaking out of an extremely tightly secured supermax prison on the moon. In this case, he’s reunited with his toxic bolt spewing symbiotic hand-scorpion-thingy, and proceeds to kill his captors - and his girlfriend who sprung him out in the first place, collateral damage - and busts out.

Please share other examples! Including any female characters, protagonists, etc. 

[loved trope] To show you how dangerous a character is, they’re shown under extreme security measures