10 most extreme places on Earth. A unicellular organism is any life form that consists of just a single cell. This group includes most life on Earth, with bacteria serving as the majority. The main groups of single celled life are bacteria, archaea (both prokaryotes), and the eukaryota (eukaryotes).
A hero (masculine) or heroine (feminine) is a person or main character of a literary work who, in the face of danger, combats adversity through impressive feats of ingenuity, bravery or strength, often sacrificing his or her own personal concerns for some greater good.
Everyone has his own definition of what a true hero is. An internet definition states that a true hero is a man of distinguished courage or ability, admired for his brave deeds and noble qualities.