Slan

A slan is a member of race of persecuted super humans in A. E. van Vogt 1946 novel of the same name. Depicted as the next stage of human evolutionary development (homo superior), slans are intellectually superior – and the ones who had tendrils in their hair were natural telepaths. In the book, they were being hounded to their deaths by mere homo sapiens, presumably because the poor saps didn't want to be replaced by the pure sups.

The descendants of Samuel Lann, slans were natural mutations, freaks who happened to have advantageous features, greater than human intelligence, strength, and endurance as a byproduct of their real advance: a nervous system of transcendent resilience and complexity, adapted to the demands of mechanistic civilization. After being beaten back by H. sapiens in one war, they established themselves on Mars and worked into control of the Earth government.

Because the central character in the story was a youth in unsympathetic surroundings, and because of the obvious similarities to fans' dreams of greatness, the unserious claim to slanhood became the Third Fandom parallel to Second Fandom's half-serious Star-Begotten claims, resulting in the catchphrase, "Fans are Slans!"

Contributors: Dr. Gafia

from Fancyclopedia 2
(vanVogt) Superman produced by mutation from humans; the word is sometimes used to mean any superhuman mutants, but in the story they were the children of Samuel Lann and their descendants. These folk had "tendrils" in the hair that gave the power of telepathy, with greater than human intelligence, strength, and endurance as a byproduct of their real advance: a nervous system of transcendent resilience and complexity, adapted to the demands of mechanistic civilization. Because the central character in the story was a youth in unsympathetic surroundings, and because of the obvious similarities to fans' dreams of greatness, the unserious claim to slanhood became the Third Fandom parallel to Second Fandom's half-serious star-begotten claims.
from Fancyclopedia 1 ca. 1944
(van Vogt) - A superman of a type different from Homo sapiens by mutation, the most noticeable characteristics being two hearts, tendrils in the hair which give the power of telepathy, and greater intelligence than H sapiens. There are tendrilless slans who lack the telepathy tendrils because their genes were tampered with, but will eventually have true slans for descendants. Slans were natural mutations, freaks who happened to have advantageous features, the children of Samuel Lann. After being beaten back by H sapiens in one war, they established themselves on Mars and worked into control of the Earth government. Because the central character in the story was a youth in unsympathetic surroundings, and because of the obvious similarities to fans' dreams of greatness, the unserious claim to slanhood has become the Third Fandom parallel to the Second Fandom's half-serious Star-Begotten claims.