Project Terror: The Giant Claw (1957)

When I was growing up in the 1970s and 1980s in San Antonio, TX, our local station, KENS 5, showed Project Terror on Friday Nights. Tonight, on Project Terror: The Giant Claw.
The Giant Claw is a 1957 American monster film from Columbia Pictures, produced by Sam Katzman, directed by Fred F. Sears, that stars Jeff Morrow and Mara Corday. Both Sears and Katzman were well known as low-budget B film genre filmmakers. The film was released as a double feature with The Night the World Exploded.
Mitch MacAfee, a civil aeronautical engineer, while engaged in a radar test flight near the North Pole, spots an unidentified flying object. Three jet fighter aircraft are scrambled to pursue and identify the object but one aircraft goes missing. Officials are initially angry at MacAfee over the loss of a pilot and jet over what they believe to be a hoax.

Mara Corday in The Giant Claw trailer screenshot
When MacAfee and mathematician Sally Caldwell fly back to New York, their aircraft also comes under attack by a UFO. With their pilot dead, they crash-land in the Adirondacks, where Pierre Broussard, a French-Canadian farmer, comes to their rescue, and reports seeing a giant monster bird he calls La Carcagne. MacAfee's report is met with bewilderment and skepticism, but the military authorities are forced to take his story seriously after several more aircraft disappear. They discover that the gigantic bird, "as big as a battleship" and purported to come from an antimatter galaxy, is responsible for all the incidents. MacAfee, Caldwell, Dr. Karol Noymann, General Considine, and General Van Buskirk work feverishly to develop a way to defeat the seemingly invincible creature.
The climactic showdown takes place in Manhattan, when the gigantic bird attacks both the Empire State Building and United Nations building. It is defeated by a special type of exotic atom, muonic atoms, deployed from the tail gun position of a B-25 bomber aircraft, which successfully collapses the creature's antimatter shield and allows missiles to hit and kill the monster. The giant bird plummets into the Atlantic Ocean outside New York City, and the last sight of it is a claw sinking beneath the ocean.