Mann's wife Katia (in a 1974 book) recalls that the idea for the story came during an actual vacation in Venice (staying at the Grand Hôtel des Bains on the Lido), which she and Thomas took in the summer of 1911:
- All the details of the story, beginning with the man at the cemetery, are taken from experience ... In the dining-room, on the very first day, we saw the Polish family, which looked exactly the way my husband described them: the girls were dressed rather stiffly and severely, and the very charming, beautiful boy of about 13 was wearing a sailor suit with an open collar and very pretty lacings. He caught my husband's attention immediately. This boy was tremendously attractive, and my husband was always watching him with his companions on the beach. He didn't pursue him through all of Venice—that he didn't do—but the boy did fascinate him, and he thought of him often ... I still remember that my uncle, Privy Counsellor Friedberg, a famous professor of canon law in Leipzig, was outraged: "What a story! And a married man with a family!"
The boy who inspired "Tadzio" was Baron Władysław Moes, whose first name was usually shortened as Władzio or just Adzio. This story was uncovered by Thomas Mann's translator, Andrzej Dołęgowski, around 1964, and was published in the German press in 1965. Some sources report that Moes himself did not learn of the connection until he saw the 1971 film version of the novel.
Władysław Moes was born on November 17, 1900 in Wierbka, the second son and fourth child of Baron Aleksander Juliusz Moes. He was aged 10 when he was in Venice, significantly younger than Tadzio in the novella. Baron Moes died on December 17, 1986 in Warsaw and is interred at the graveyard of Pilica, Silesian Voivodeship. He was the subject of a biography, The Real Tadzio (Short Books, 2001) by Gilbert Adair.