In A Nutshell
The great white shark is a terrifying predator, but it is not at the top of the food chain. The orca, or killer whale, has been observed attacking and eating the shark. In one highly publicized incident, a female orca was observed holding one of the sharks upside-down and causing it to suffocate.
The Whole Bushel
The great white shark is probably the closest earthly thing we have to an actual monster. The largest specimens can exceed 6 meters (20 ft) and weigh over 2,200 kilograms (5,000 lbs). While measuring the bite force of this beast is fraught with obvious difficulties, a 2008 computer model ascertained that a 6.4-meter (21 ft) shark could bite with a force approaching 4,000 lbs per square inch. Great whites are not nearly so dangerous to humans as the Jaws films might suggest, but they have attacked more people than any other species of shark. Their teeth cut through flesh like a hot knife through butter, and yet they are not the baddest creature in the ocean.
Normally, the only thing a great white shark has to worry about is a bigger great white. Very occasionally, however, they run across orcas (killer whales) and the results are disastrous for the shark. We see orcas through the Sea World lens of trained monkeys, but in the wild these animals are unstoppable apex predators, hunting in organized pods likened to wolfpacks. The largest male orca recorded was 9.8 meters (32 ft) long and weighed 10,000 kilograms (22,000 lbs). Different populations around the world have varied diets, with some groups eating fish, whales, or seals.
Certainly, the great white shark is not seen by orcas as a typical prey item; it is believed that in the rare instances the two come into contact, they are probably competing for the same resources. One incident occurred on October 4, 1997 off the coast of California. A female orca flipped a great white upside-down and held it in place, suffocating the shark. The orca then feasted on its liver. Following the attack, the scent of death in the water caused every great white shark in the area to flee.
Show Me The Proof
Great white shark versus orca
National Geographic: Great White Sharks
Sea World: Killer Whales