Greer Grant was a University of Chicago sophomore when she met rookie policeman Bill Nelson. They fell in love and married. Greer dropped out of college, at Bill's insistence. When Bill was killed in an off-duty shooting, Greer was left on her own. When she tried to find a job, the only positions she was offered were typists or clerks. One day, she ran into her old physics professor, Joanne Tumulo. She remembered her old pupil and hired Greer as her lab assistant. Greer also returned to college.

After several months, Dr. Tumulo revealed she'd been working on a private project to allow women to achieve their full mental and physical potential, despite the handicaps that society placed on them. She wanted Greer to be the first subject.

Due to lack of funds, Dr. Tumulo had made an arrangement with an eccentric named Malcolm Donalbain. Donalbain was a fanatic on physical conditioning. He had agreed to sponsor the research. However, he overrode Dr. Tumulo's choice and insisted his protogee, Shirlee Bryant, be their "first lovely guinea pig." The doctor wanted to cancel the experiment, but Greer persuaded her to secretly test Greer as well as Shirlee. Both women emerged from the treatments with superhuman physical and mental abilities.

Donalbain planned to use those powers for his own purposes. He told Shirlee she was to be the first of hundreds of enhanced women who would work in his clubs. Using the clubs as a front, Donalbain's force would seize control of the country. He gave her a uniform to wear, a yellow catsuit with blue claws, gloves, and sash. Shirlee balked at donning a cat-earred cowl, but Donalbain told her that it mechanically enhanced her hearing and night vision. Reassured, she finished off the outfit with a studded blue collar. The will-nullifier forced her to obey Donalbain, much to his satisfaction. He ordered Shirlee to demonstrate her new athletic abilities, but she fell to her death.

Donalbain had his henchmen dynamite Dr. Tumulo's lab to eliminate any incriminating evidence. The doctor was critically injured in the explosion. Greer donned one of the Cat uniforms to put an end to his plans.

Greer continued her adventures, defeating the Owl, Commander Kraken, Man-Bull, and the Mankiller. One day she came home to interrupt a kidnapping attempt on the convalescing Dr. Tumulo by Hydra agents. Greer was shot with an "alpha radiation" pistol while driving off the agents. Dr. Tumulo saved Greer's life with a mystic ritual that bound the soul of one of the Cat People to her. The reborn Tigra abandoned both her previous identities.