A lot of beautiful plants are toxic for cats : Lilies, tulips, aloe vera, peonies, daffodils, snake plants, english ivy, hyacinth and a lot more! I hope cat owners do a quick Google search before purchasing new houseplants.
The one I have known for long that's harmful to cats are lilies, hyacinth and aloe Vera. I am not a fan of buying houseplants for decoration or beautifying my home so I always avoid them like plague.