If nobody else, Obi-Wan. Although the exchange at the Lars household over dinner suggests that Owen and Beru didn’t exactly hide his father’s name from him. Since “Anakin” doesn’t appear at all in the script until after the twist, it’s likely that there wasn’t a firm name for him until ROTJ.

imsdb.com/scripts/Star-Wars-A-New-Hope.html imsdb.com/…/Star-Wars-The-Empire-Strikes-Back.htm… imsdb.com/…/Star-Wars-Return-of-the-Jedi.html

Luke definitely knew he had a father, though. And had an idea of who he was from the aunt and uncle who raised him, Obi-Wan, and even the rebel pilots.