The term "glass cannon" refers to a character who deals out huge damage but is unable to take much in return. This term most often applies to fighters who can deal very high damage but have very low health to compensate.

The name itself is saying that you are a cannon who can be very destructive but so much as a single knock can shatter you,

Melee characters can be glass cannons as well, though they should probably get a different term, just since "cannon" is associated with ranged attacks.

Heroes That can be Built as 'Glass Cannons'

Demon hunter icon Demon Hunter (Lebmont)

Dark elf exile icon Dark Elf Exile (Ihaelryna)

Inquisitor icon Inquisitor (Debronee)

Aria Wind Dancer (Aria Eagleheart)

Nuutt Child of the Forest (Nuutt)