A mind-dancer is a form of mystical telepathy in the now-defunct City of Heroes MMO.
As with all other forms of control, telepathy can be biological, technological, or mystical in origin. The most recognized form of telepathy is biological, with those being born with the ability as a form of mutation. Technological telepathy has always been theoretical. But mystical telepathy is probably the best kept secret.
The very first person to identify "mind-dancing" as a mystical art itself was an operative who called herself "Mind-Dancer". Much of her past has been "muddled", thanks in no small part to her own skills. But it is believed that, like many others in her situation, she's used her ability to retain the illusion of immortality and youth.
Once she established herself as a telepath, she began looking for others like her. She measured their potential, recruited them, trained them, and then encouraged them to seek out others.
It is believed that a mind-dancer was involved in the Salem Witch Trials, although it is uncertain if they were the victims or the accusers. (Or both.) Since then, however, mind-dancers operated in secret.
Today, they are considered whispered rumors in the mystical world. If you are one, you don't brag about it.