Cast members have been careful not to leak spoilers in the run-up to the final season of “Game of Thrones,” the fantasy HBO series, dropping only cryptic, tantalizing clues to eager fans.

Many viewers have wondered about the fate of their favorite characters since the first novel in George R.R. Martin’s “A Song of Ice and Fire” debuted in 1996. Yet, fans must wait until the end of this final season, which premieres April 14, to discover who will get...