We've seen actresses playing characters 10 years younger before but have never heard of anyone playing a character more than 3 times younger than their age. 

At 59, this Chinese actress is playing a 16-year-old girl in a historical drama, and she even has kissing scenes with a man 21 years younger than she is.

Liu Xiaoqing is a famous actress in China, and this isn't the first time she's played such a young character. Liu also once played Emperor Wu, China's only female emperor in recorded history, from the age of 16 to 82, although that was in 1995.