Albert Uderzo, the illustrator of the famous Asterix comics, died on Tuesday, The Guardian reported. He was 92.

The French comic book artist died of a heart attack at his home in Neuilly, France, Uderzo’s son-in-law Bernard de Choisy told AFP. “He had been very tired for several weeks,” he said.

Uderzo and his friend and writer René Goscinny created the Asterix comics in 1959. The series revolves around the adventures of Asterix, a shrewd Gaulish warrior fighting the Roman Empire with his best friend, the indomitable but nimble-brained Obelix and dog Dogmatix. The books have sold 370 million copies worldwide, in dozens of languages, and several stories have been turned into cartoons and feature films.

The series has extended into 38 books, with “Asterix and the Chieftain’s Daughter” being the latest edition that was published last year. Uderzo stopped illustrating the series in 2011. After the death of his partner Goscinny in 1977, he had been handling the writing of the comics as well.

Nearly 1.6 million copies of “The Chieftain’s Daughter” were sold last year in France alone, putting it at the top of best-seller lists.

The two men are considered the founding fathers of modern comics and graphic novels.