What are some of the most toxic and deadly poisons known to mankind? And, what are their effects?

Polonium 210, botulinum toxin, and the toxin from the poison frog are perhaps the most toxic and deadly poisons known to mankind. Polonium 210 is so radioactive that a gram of it can kill 10 million people and the few that will survive will undeniably have cancer. Botulinum toxin is the most lethal toxin. A few drops could kill billions of people. It causes botulism which weakens the muscles of the body and eventually leads to death. The poison frog is used to add poison to arrows of hunters in South America. Simply touching the small frog will surely cause death either by cardiac arrest or lung failure.