Courtney is the stepdaughter of Pat Dugan. She found Sylvester Pemberton's cosmic converter belt in her stepfather's belongings and donned the costume in order to annoy him as partial revenge for marrying her mother and supposedly forcing the family to move from Los Angeles to Blue Valley, Nebraska. Dugan, a skilled mechanic, designed and built S.T.R.I.P.E., an armored Robot which he rides in to accompany and protect her. Eventually, she joined the Justice Society of America and, after being given Starman's gravity rod by Jack Knight, changed her identity to Stargirl.