Putting Helen Slater in to her first ever film role as a character as popular as Supergirl was always going to be a terrible idea. Some people think that the Supergirl movie was a cheap, low-budget spin-off of the Superman movies and therefore getting a minor actress made sense, but this was a $35 million budget movie in 1984 - it was far from being low budget, so such a risk was crazy. Slater was likeable enough - don't think we're saying anything to the contrary - but she just wasn't interesting enough. She lacked the acting chops to live up to the reputation that the mighty Christopher Reeve had brought to Kryptonian movie heroes. She spent the entire movie being wide-eyed and cheery, but lacked depth and substance and ended up just being a bit boring. She was also playing opposite accomplished talent like Faye Dunaway, Mia Farrow and Peter O'Toole and she was simply outshone.
