Absolutely! Yew trees are incredibly poisonous to humans except for the fleshy part of the berries. You should avoid them though as the rest of the tree including the seeds in the berries are poisonous, and can cause rashes when you touch it.
Some plants it can have several chemicals that are both dangerous and also useful depending on how they are used and how concentrated they are. So belladonna/deadly nightshade has several very dangerous alkaloids in it, hence the name, but also has scopolamine in it which can be used in medicines to treat sickness. Again, please avoid this plant, and if you see it in the garden either get help to remove it or wear gloves and wash your hands, as the whole plant is poisonous.