Princess Leia is the original female protagonist of the Star Wars saga.
She encounters Perry the Rebelpus when she sneaks the plans for the Death Star into R2-D2.Phineas and Ferb see the broken hologram of her from the droid. She is the senator of Alderaan, and leader of the Rebel Alliance. She also appeared dancing with Perry in Rebel, Let's Go!
She has the same apperance on Episode IV: A New Hope.