Mr. — Back

The most common reference is the 16-episode MBC TV series starring Shin Ha-kyun and Jang Na-ra.

Choi Go-bong, a greedy 70-year-old hotel conglomerate president, magically transforms into a 30-year-old man.

In the world of Bitcoin, "Mr. Back" refers to , a prominent British cryptographer. Mr. Back

A mini web series by Certified Rascals that follows the workplace chaos caused by an overzealous backup manager named Naresh.

He is the creator of Hashcash , a proof-of-work system cited in the original Bitcoin whitepaper by Satoshi Nakamoto. The most common reference is the 16-episode MBC

A breezy romantic fantasy with comedic elements, often highlighting the protagonist's elderly habits in a young body.

My Quest to Solve Bitcoin’s Great Mystery - The New York Times Back" refers to , a prominent British cryptographer

The name is also used for smaller web-based projects and social media personas: