Your hero (a player character), and unique allies, villains, and monsters are collectively called “Wild Cards.” These beings have a little better chance at doing things, are a little tougher to put down, and are generally more detailed than common guards, minions, or lackeys–collectively called “Extras.”
Wild Cards are noted with a design of some sort before their name, like this:
The actual Wild Card symbol varies and is usually themed for the particular setting, such as a skull-and-crossbones for a pirate game like 50 Fathoms, or the visage of the puritan himself in Solomon Kane®, but a symbol in front of the name always means the character is a Wild Card.
Besides your own characters, it's up to the Game Master to decide which characters are Wild Cards. The sergeant of the City Watch probably isn't a Wild Card, but Sergeant Grimlock of the City Watch, a veteran of many wars and an important character in your campaign, certainly is. Skytch the Dragon is also a Wild Card, though his three young wyrms aren't. You'll see the difference between Wild Cards and Extras as you continue to read, but for later reference, the differences are:
Savage Worlds Deluxe Edition p. 70