Here is a caterpillar with a fantastic name, and an even more fantastic look. The Stinging Rose caterpillar, found in forests of the eastern US, is a mere one inch long and is brightly colored. But what catches the eye more than the vivid yellows and reds are the spined tubercles jutting from its sides. University of Arkansas notes that the black tips on these spines release poison. If you touch one, the tips break off and will give you a skin irritation nearly on par with the Saddleback caterpillar.
Toxic but nonetheless important to its ecosystem, it (and the moth it turns into) is considered a species of conservation concern.