An update might be a good idea.

Otherwise the information here is great!

The strongest synthetic fiber is carbon nanotubes.
The strongest organic fiber is spider silk. Both are stronger than silk, but I don’t know if the nanotubes or spider silk is stronger.
Zylon®, the world’s strongest fiber, contradicts almost everything we know about fibers and fabrics. Zylon is made by mixing a polymer called PBO (para-phenylene benzobisoxazole), while forcing it through a spinning machine.
The World’s Strongest Fiber
Toyobo Co., Ltd.
Zylon®, the world’s strongest fiber, contradicts almost everything we know about fibers and fabrics. Zylon is made by mixing a polymer called PBO (para-phenylene benzobisoxazole), while forcing it through a spinning machine. PBO has a chemical structure that is difficult to process, but a major manufacturer of fibers, Toyobo Co., Ltd., has succeeded in producing this “super fiber.” Zylon’s tensile strength is about 10 times that of steel—a Zylon thread only 1 mm thick can hold an object weighing 450 kg! Zylon has excellent flame resistance, withstanding temperatures up to 650°C, and is more impact-resistant than even steel or carbon.
Zylon’s superlative properties are put to good use in protective clothing like firefighters’ uniforms, heat-resistant clothing and bulletproof vests. Zylon is also used as a heat-resistant industrial material, and in the manufacture of optical fiber cables. In 2001, the National Aeronautics and Space Administration (NASA) of the United States used it as a reinforcing material for a space observation balloon.
Saito Masakazu of Toyobo says, “The principles on which Zylon is based were discovered in the United States more than 20 years ago, but it’s not easy to make commercial products using it. We were able to do so only after applying Japan’s fiber technologies and manufacturing techniques.”