The business end of the most massive spider in existence, the "Goliath Bird-Eater".
These amazing arachnids can grow to be approximately 1-foot in legspan and weigh close to 200 grammes. (Although I am convinced that there are some adult females out there that exceed that weight)
With the most massive spider in the world, comes the largest fangs. In the case of the Goliath, these can grow to be an inch and a half long, and although their venom is quite mild, those fangs are long enough and sharp enough to do some serious damage. Capable of penetrating completely through fingernails, shearing cartilage, tearing muscle tissue, and piercing bone. So, although the venom is not going to be too bad, you're still going to be in for a whole lot of hurt!
This particular image is of the fangs from an adult female Theraphosa stirmi.