You’re most likely asking about “A” from Pretty Little Liars , since that’s the most common context for “who A is.”

Short direct answer

  • In the original Pretty Little Liars TV series, the first big reveal of who “A” is happens in Season 2, Episode 25 (“UnmAsked”) , when Mona Vanderwaal is unmasked as A.
  • Later seasons reveal new “A” identities (often called “Big A” or “Uber A”), so you “find out who A is” multiple times across the show’s run.

How the A reveals work

  • The show is structured so that “A” is more of a role than a single permanent person, which is why the mystery keeps resetting.
  • Mona is the original A, but later reveals include Charlotte/CeCe Drake (often called “Big A”), and then Alex Drake as “Uber A” in the series finale, so different phases of the story answer “who A is” differently.

If you’re still watching (no-heavy-spoilers version)

If you just want to know when you’ll get an answer without too many details:

  • You get the first real payoff in the Season 2 finale.
  • The biggest backstory-heavy reveal is much later, around the Season 6 mid-season finale , when “Big A” is explained.

If you meant a different show, book, or game with an “A” mystery, say which one (title + season or episode if it’s TV), and the answer can be pinned down for that specific story.

Information gathered from public forums or data available on the internet and portrayed here.