There are definitely a few plausible fills depending on the crossword’s length and how stingy the setter is. For a short 4-letter slot the usual fill is LEIA, which is the go-to because 'Star Wars' practically screams her name. If the grid needs five letters, PADME is often used — she was queen and later a senator, and some puzzles will clue her as a royal figure rather than strictly a princess.
Longer slots open up ORGANA (6 letters) or AMIDALA (7 letters), which are useful when the constructor wants a surname or a slightly more obscure twist. Sometimes you'll even see LEIAORGANA or LEIAORGANASOLO in themed or gimmicky puzzles, but those are rare and usually flagged by the clue length. My trick is to check crossings first: a single wrong crossing can flip you from LEIA to PADME in a heartbeat. I still get a kick when the grid rewards a pop-culture detail, so keep enjoying the hunt.