Barium:

Barium was first discovered in 1774 by Schelle, the elusive supervilian had been undiscovered long enough and was revealed in the dark when he let off a bright glow. Barium a strong and agile vilian disguises himself in pale yellow. This active metal has an atomic radius of 222 pm and a density of 3.51 g. To his advantage, Barium is almost invisible and can rarely be found roaming the streets at night due to his intolerance to air. Barium is highly reactive and will never hesitate to join a fight if he is insulted. And his enemies should be scared, Barium has the ability to suck away oxygen from his captors like a vacume. Barium is dangerous to others, his presence alone can be fatal to those around him. Unlike other super people Barium can shoot green fireworks from his eyes to light his paths at night. Barium can also turn stone to glass with his touch and can withstand heat up to 1300 F. With a low electronegativity of 0.89 Barium can move quickly when running away for the disasters he causes.

Sources:
http://www.globalhealingcenter.com/heavy-metals/dangers-of-barium
http://environmentalchemistry.com/yogi/periodic/Ba.html#Chemical