Tartaglione thus began a long association with Marvel that found him penciling suspense, adventure, sports and crime stories — signing his work a variety of ways including "Tartag", "Tar", "Leone" and "JT" — though he was most prolific in romance titles, illustrating more than 120.

[4][6] With the exception of an occasional item such as the cover of Dazzler #12, Tartaglione returned to penciling for the first time in years with the 64-page Marvel Comics biography The Life of Pope John Paul II (1982), written by Steven Grant and Mieczyslaw Malinski, and inked by Joe Sinnott.

Comics historian Mark Evanier wrote that Tartaglione at Marvel "became the 'go-to' guy when a project came along that required historical research and/or spiritual themes.

He was therefore the perfect artist when, in 1982, Marvel issued a comic-book biography of Pope John Paul II that through various religious channels sold well into the millions, leading to a follow-up book on Mother Teresa".

[4] By the early 1990s, Tartaglione had retired to Centerport, New York, but he was lured back to the industry by Personality Comics, a local up-and-coming publisher.

[3] According to family friend and comics creator Billy Tucci, Tartaglione's artist daughter, Mary Beth, "actually finished this week's inks on the Spider-Man strips today and sent them out, closing out his last job.