Name: UNDYNE
Monster Type: TREMENDOUSLY STRONG FISH WOMAN FUHUHU
Gender: Does it really matter? Female.
Occupation: Captain of the Royal Guard and the bodyguard to the Ambassador between humans and monsters.
(PROFESSIONAL BOULDER SUPLEXER)
Weapon?: Energy spear
Armor?: I used to have armor. But really, it was just for looks. 
Magic: Spears of Justice! (Undyne can launch just one, or multiple
Green Attack (keeps the soul from moving, and the opponent has to guide the shield around to keep from being damaged.)
SUPLEX A BOULDER
Personality: I'm rash, I'm brash, and I and one of the toughest MONSTERS FROM THE UNDERGROUND! FUHUHU! Also, I'f you're a nerd... YOU BETTER NOT EVEN THINK ABOUT GETTING INTO MY ROOM! ... Only a few nerds can get in there.
Bio: Undyne, from a young age, was a fiery kid, already challenging those around her and ready to attack just about anyone. It wasn't until she was easily bested by Asgore that she actually started to train. Day after day, she got better, learning how to utilize everything she had to be as effective as possible. One day, She finally beat Asgore, but rather than feeling good about winning, she felt bad. He was just a giant fuzzy pushover that happened to be incredibly strong. Since then, she became captain of the royal guard, and has been training Papyrus to not only be a great warrior, but also a chef.

Since Frisk came around and saved the underground, Undyne has been working as their bodyguard as well. 
Appearance:[img]http://41.media.tumblr.com/8f088396a7c6d34d98f341fe3de910e7/tumblr_nwj10qOgke1sxz4nbo1_500.png[/img]