Tomorrow Girl is a superhero who regularly defends the town of Quagmire. Although somewhat of a Supergirl parody, she is not actually an alien. She is in fact a sythoid; a kind of artificial construct designed to resemble a human right down to the cell structure.
May came from a dystopian future where an artificial intelligent race has enslaved mankind. It used a government controlled cloud blocked out the sun. She was sent back in time to capture Jeremy Feeple and bring him back to her time as he was crucial for the survival of that race. She was defeated, and ended up joining time traveller Professor Azland.
She and her adopted "father" Tomorrow Man work together to defend the town of Quagmire. May dated Ricky Feeple for a while. Their relationship did not last as various events kept them apart. By the time they had been reunited again, Ricky was married and had completed his ninja training.