In olden times, kings and queens had royal poisoners on hand to get rid of inconvenient people. They were good at what they did. For example, they could lightly dust a letter or page of a book with a powder that would kill whoever touched it.
Politically-motivated poisoning is back in vogue. New York reports that "Kim Jong-nam, the older half-brother of North Korean leader Kim Jong-un, was killed in a Malaysian airport Monday after he was sprayed in the face with an unknown liquid, police said Tuesday."
The oldest son of Kim Jong-il, Kim Jong-nam was seen as the heir apparent in North Korea throughout the 1990s. But that reportedly changed after he was caught with a forged Dominican passport in 2001 as he was trying to sneak his way into Japan to attend Tokyo Disneyland. The subsequent fallout from that incident led to Kim Jong-un's grooming to take over for the Dear Leader.