Trebek who once hosted this puzzle's theme

ALEX

This legendary "Jeopardy!" host shared his first name with a certain Greek warrior king.

This clue refers to Alex Trebek, the longtime host of Jeopardy!, which is a show built around puzzle-style questions like crosswords. The phrase "this puzzle's theme" hints at Jeopardy! itself, tying the clue to its famous host. Since the answer is just his first name, "ALEX" fits perfectly as a short, direct response. It’s a nod to his iconic role without needing extra words.