All spiders have fangs! And, yes, they almost all have venom in them. Lucky for us, most spider poison will not harm people because it is quite weak. Most spiders use their venom to paralyze its insect victim long enough to devour it. For other spiders, their poison is strong enough to kill their prey. Of course, this also comes in handy when being attacked by a predator.
There are a few spiders with poison strong enough to cause pain or even some nerve damage in humans. These spiders include the Black Widow and the Brown Recluse spiders. If left untreated, death could result.
People usually associate Tarantulas with the people-killing kind of poison. This is untrue. They have small poison glands and will be about as painful as a hornet or bee sting.