Che Guevara, he was an Argentine Marxist revolutionary and guerilla. Close friend of Fidel Castro and played an important role in the Cuban revolution.
This particular image of him is a famous photograph taken during a memorial service for the victims of a ship that exploded. It’s become an iconic image presumably due to his somber expression, but is also associated with rebellion when used commercially, which is of course a weird irony.
He remains a controversial figure. National hero in Cuba, and regarded by those of a socialist and communist persuasion as an anti-imperialist, anti-capitalist hero and champion of the poor. Liberals and conservatives on the other hand view him as a brutal murderer.
He was a complex character that you’d need to read about in depth to form an opinion on.