According to the American Psychiatric Association which names all the phobias and diseases related to mental illnesses, a phobia is a persistent, irrational fear of a person, situation or object. In many cases the person who is experiencing the phobia has an overwhelming sense of fear and believes they are in danger. 

Phobias are considered one of the most widespread mental disorders in the United States and can have a devastating impact on the people they affect.

The lists of phobias are long and run the gambit from Achluophobia – the fear of darkness to the fear of animals – Zoophobia.

The list of all phobias for natural things or things found in nature is not quite as long as the other lists of phobias. Beginning with the fear of flowers – Anthrophobia; Arachnophobia is the fear of spiders; Astraphobia is the fear of thunder and lightening; Barophobia is the fear of gravity; Botanophobia is the fear of plants; Chionphobia is the fear of snow; Dendrophobia is the fear of trees; Heliophobia is the fear of the sun; Hydrophobia is the fear of water; Lilapsophobia is the fear of hurricanes and tornadoes; Noctiphobia is the fear of night; Ombrophobia is the fear of rain; Pteridophobia is the fear of ferns; Pyrophobia is the fear of fire; Selenophobia is the fear of the moon and Tonitrophibia is the fear of thunder;

There are many phobias that seem irrational to the ordinary person, but can be crippling to the person with the fear or phobia of the items. This list of phobias include – Acrophobia, the fear of heights; Agliophobia, the fear of pain – which we all have a little of to some degree; Agoraphobia, the fear of open spaces or crowds; Aichmophobia, the fear of sharp objects or needles; Amaxophobia, the fear of riding in a car; Anginophobia, the fear of angina or chocking; Aphenphosmphobia, the fear of being touched; Aritmophobia is the fear of numbers; Ataxophobia is the fear of disorder and untidiness; Atelophobia, the fear of imperfection; Atychiphobia is the fear of failure; Autophobia is the fear of being alone;  Bathmophobia, the fear of steep slopes or stairs; Bibliophobia is the fear of books; Cacophobia is the fear of ugliness; Catagelophobia is the fear of being ridiculed; the fear of mirrors is Catoptrophobia; fear of colors is Chromophobia; the fear of clocks is Chronomentrophobia; Coulrophobia is the fear of clowns which many people have in common; Dentophobia is the fear of dentists; Dystychiphobia is the fear of accidents; Ecophobia is the fear of the home; Ephebiphobia is the fear of teenagers; Genuphobia is the fear of knees; the fear of speaking is Glossophobia and the fear of women is Gynophobia. 

Fear or phobias concerning animals are pretty high on the list of what people fear and they cross many boarders, sexes and classes. Some of the animal phobias include Arachnophobia, the fear of spiders; Batrachophobia is the fear of amphibians; Cynophobia is the fear of dogs; Elurophobia is the fear of cats; Entomophobia, the fear of insects, Equinophobia is the fear of horses and Herpetophobia is the fear of reptiles.These lists of phobias are not complete but will give you some idea of the many, many phobia lists available for what scares people the most.