Hair

A Beard is the facial hair that grows on the face of most humannoid males - including humans, Vulcans, Klingons, and Bajorans. Some males choose to grow full beards, other males do not grow full beards or only grow partial beards, and control the growth of beards by shaving.

At various points in history, those with beards have had the positive attributes sign of wisdom, virility, or being of refined character associated with them. At other times, those with beards have had negative attributes - such as a lack of cleanliness or eccentricity. Dr. Beverly Crusher felt that with the availability of razors that beards were an affectation. (TNG episode The Quality of Life).

In our universe most Vulcan males did not generally wear beards. Vulcans had a saying, "A beard often reveals more than it conceals." Some Vulcans felt that a male with a beard had something to hide. (TOS novel Probe). However, this did not stop some healers and masters from growing beards. (VOY episode Gravity). One famous Vulcan who maintained a full beard was Sybok. (Star Trek V: The Final Frontier). In the mirror universe, bearded Vulcans were much more common. Notable Vulcans from that universe who wore beards included Spock and Soval. (TOS episode Mirror, Mirror and ENT episode In A Mirror, Darkly, Part II).

Dr. Leonard McCoy left Starfleet after the first five year mission on the USS Enterprise (NCC-1701) under James T. Kirk's command. He took the time to grow a full beard. Shortly after returning to Starfleet when the refitted Enterprise was launched, Dr. McCoy shaved his beard. (Star Trek: The Motion Picture).

In the 24th century, Commander William T. Riker decided to grow a beard in 2365 after tiring of people commenting on how young he looked. (TNG episode The Pegasus). While on shore leave, he allowed his beard to grow, and upon returning to the USS Enterprise (NCC-1701-D) he trimmed and styled the beard. (TNG novel Strike Zone). Riker kept the beard for a number of years, but shaved it off in 2375. (Star Trek: Insurrection) By 2379, Riker once again had a full beard. (Star Trek: Nemesis)

Riker's transporter duplicate Thomas Riker had also grown a beard while trapped on Nervala IV. After being rescued by the Enterprise, Thomas learned of William Riker's existence. He decided to leave the Enterprise for a posting on board the USS Gandhi. (TNG episode Second Chances) To further differentiate himself from William Riker, Riker shaved off most of his beard, and maintained a goatee instead. (DS9 episode Defiant).

Shortly after Commander Riker grew his beard, Lt. Commander Data also decided to experiment with growing his own beard. After seeing the reaction of Lieutenant Geordi LaForge and Deanna Troi to what he had called his "new look", Data decided not to keep his beard. (TNG episode The Schizoid Man)