Fear
Fear or fright was an emotion sensed by most lifeforms. It was initiated when an individual perceives a danger, such as a threat of injury or death. The fear of a specific object, situation, person, or group was known as a phobia. Common fear triggers included heights. (, ; )

Biological response 
Within Humans, fear leads to the release of adrenaline levels within the body. Pavel Chekov was spared the effects of radiation-induced hyperaccelerated aging when the release of adrenaline from his momentary fear of discovering a dead body on Gamma Hydra IV protected him from the radiation on the planet. ()

Deanna Troi experienced a surge of fear when a Paxan momentarily took control of her body, though the only trace left were signs of  and higher than  adrenaline by-products. Doctor Beverly Crusher noted these were all normal reactions to a sudden fright. ()

History 
In 2151, Commander  joked that Travis Mayweather's ghost story scared off the s after Crewman Cutler noticed that nearby fireflies had disappeared. Tucker later stated that Vulcan scientist Mister Velik scared the hell of him in tenth grade biology class. ()

That same year, the Novan Nadet screamed in fear while being treated in the imaging chamber in sickbay aboard . ()

In 2258 in the alternate reality,  described the purpose of his  as being to experience fear, specifically fear in the face of certain death, and to accept that fear and maintain control of oneself and one's crew. ()
In 2268 after the Starnes Exploration Party committed mass suicide, their orphaned children displayed no indications of grief or fear. ()

According to Nyota Uhura in 2269, Humans in the 23rd century learned not to fear words. ()

In 2364, Commander William T. Riker correctly answered the challenge of Portal 63, stating that fear was the enemy, the only true enemy. ()

That same year, Captain Jean-Luc Picard cited fear as the reason he did not keep his appointment with Jenice Manheim at the Café des Artistes, fear that he would lose his resolve or might even lose himself. Manheim, however, correctly intuited that his greatest fear was that life with her would have somehow made him ordinary. ()

In conversation with Lieutenant Commander Data, Captain Picard remarked that "fear can be a powerful motivator." In Charles Dickens' story "A Christmas Carol," fear is used to motivate the protagonist, Ebenezer Scrooge, to reform his character, by showing him that an eternity of torment awaits him if he continues with his current character. By the same token, Picard speculates, the early ancestors of the people of Ventax II used the legend of Ardra, a mythical figure similar to Earth's Devil, to inspire fear in support of planetary-wide reforms. Unfortunately, a con artist posing as Ardra was able to exploit this same fear a thousand years later. ()

In 2368, Captain Picard stated that he'd never been afraid to reevaluate his convictions, but now he had twenty million reasons to do so, as Penthara IV was slowly turning to ice which would result in thousands of deaths if not prevented, but Lieutenant Commander Geordi La Forge's solution to stop it could kill all life on the planet if it were not successful. ()

Franklin D. Roosevelt once said, "The only thing we have to fear is fear itself." Harry Kim discovered that this is literally true when he encountered a psychopathic clown character, an embodiment of the emotion. Captain Kathryn Janeway, meanwhile, sought a way to reach the Clown, wondering whether there was more to fear than just a demand to simply exist. The Doctor noted that fear could provide pleasure by allowing one to seek the boundaries of one's existence and Janeway pondered, "But what does fear seek at the end of the ride?" ()

In her captain's log in 2373, Captain Janeway stated, regarding the 's recent encounters with the Borg and Species 8472, "The Northwest Passage is only one day away and I won't allow fear to undermine this crew's sense of purpose, even if that fear is justified." ()

Seven of Nine felt that the Omega Directive was the result of Starfleet's ignorance and fear regarding the omega molecule, but Captain Janeway felt that "sometimes fear should be respected." ()

In 2399, chastising Starfleet's decision to ban synths, Jean-Luc Picard stated to Cristóbal Rios that fear was the great destroyer. ()

Phobias 
Agoraphobia
Aquaphobia
Aviophobia
Claustrophobia
Nihiliphobia
Transporter phobia
Xenophobia

External links 
 
 

de:Angst
Emotions