All tarantulas are venomous. Some old world species are quite potent as well.
Our Texas Brown Tarantulas are non-aggressive. It is rare that one will bite a person -- you can let them walk on your hands/arms (if you so choose). In the rare occasion one bites you, it's no more dangerous than a bee sting.
Here is one I caught in my garage, took to a nearby ranch, and released.
The dangerous spiders in Texas are the Brown Recluse. They can mess you up.
We have scorpions in Texas, too, but not as far North as where I live. There were lots of them at my parent's house when they lived in San Antonio. Their sting hurts, and can leave a nasty wound, but again, not likely to kill a person or even a pet.