Daphne Blake

She is the most fashionable (and now the strongest) member of Mystery Inc.

History
After the Mystery Inc. broke up, she decided to become stronger not to be a "damsel in distress". Later she met with Mystery Inc. again, because they all were invited on a same island to solve a mystery. Later they investigated a haunted castle because she met a strange guy who warned her not to go. She found a strange triangle-shaped thing there.
 * Scooby-Doo