Jack Gleeson (born 20 May 1992) is a retired Irish actor, best known for his portrayal of Joffrey Baratheon in the HBO television series Game of Thrones.\n\nAnswer this question: who played joffrey lannister in game of thrones?
Let's think step by step.
Jack Gleeson ( born 20 May 1992 )
The important part for answering this question is: Jack Gleeson (born 20 May 1992) is a retired Irish actor, best known for his portrayal of Joffrey Baratheon in the HBO television series Game of Thrones.

.

Therefore, the answer is Jack Gleeson ( born 20 May 1992 )