Horsehair worms, aka hairsnakes or Gordian worms, Order Gordioidea, Phylum Nematomorpha. Found throughout the world.

Although alien in appearance, these worms are parasitoids of arthropods in their larval stage and are not harmful to humans or other mammals. Adult worms are free-living, meaning they do not require a host, and they do not feed. Most are only a few inches long, but in extreme cases they can reach over two meters in length while remaining only 1 to 3 millimeters in diameter.

Photos 1-2 by Andreas Kay, 3 by mingchungchiu, 4-5 by kai_pirinha, 6 by diego4nature, and 7-8 by robirwin

A short but informative video below! Just the worm, no injured host insect.