Vulcans, sometimes referred to as Vulcanians, are a fictional extraterrestrial humanoid species in the Star Trek media franchise. They are noted for their strict adherence to logic and reason and suppression of emotion. Known for their pronounced eyebrows and pointed ears, they originate from the fictional planet Vulcan. In the Star Trek universe, they were the first extraterrestrial species to make contact with humans.

The most notable Vulcan character is Spock, first played by actor Leonard Nimoy in Star Trek: The Original Series (1966–1969). Some aspects of this fictional alien race that have entered popular culture are their pointy ears, the Vulcan salute, the Vulcan nerve pinch, and their adherence to logical thinking and disdain for emotion.

A 2019 journal article, Science Fiction and the Abolition of Man argued that many science fiction characters such as Vulcans of Star Trek are based on the ideas of The Abolition of Man by C. S. Lewis.

The Vulcan Mister Spock first appeared in the original 1965 Star Trek pilot, "The Cage", shown to studio executives. Show creator Gene Roddenberry revealed in 1964 that he wanted an alien as part of the ship's crew, but knew that budget restraints would limit make-up choices. He chose actor Leonard Nimoy because of his "high Slavic cheekbones and interesting face" and "with those cheekbones some sort of pointed ear might go well." Nimoy later commented that Roddenberry felt the presence of an alien would "establish that we were in the 23rd century and that interplanetary travel was an established fact."

The Vulcan salutation is that of the Jewish priestly blessing: a hand gesture consisting of a raised hand with the palm forward and the thumb extended, while the fingers are parted between the middle and ring finger. Typically, the phrase "live long and prosper" is uttered when making the salute, adapting the priestly blessing "may the Lord bless you and keep you." An appropriate reply would be to return the gesture and utter either "live long and prosper", or "peace and long life".

Vulcans are depicted as similar in appearance to humans, as budget constraints in The Original Series did not allow for elaborate make-up. All Vulcans have arched and upswept eyebrows and pointy ears. White actors portraying Vulcans are given a yellowish hue to their skin. A Vulcan's on-screen blood is green due to copper-based hemocyanin. Vulcans are said to possess an inner eyelid, or nictitating membrane, which protects their vision from bright light, an evolutionary trait developed due to the fictional planet Vulcan being so close to its sun. In addition, their heart is located on the right side of the torso, between the ribs and pelvis; as Dr. McCoy once says about Spock after the Vulcan has been shot through the chest: "Lucky his heart's where his liver should be, or he'd be dead now."

Vulcans are vegetarians by choice and were omnivores in ages past. It is a Vulcan custom for guests in the home to prepare meals for their hosts.

Vulcans are said to not drink alcohol, though they are often depicted as doing so.