A eunuch is a castrated human male. The castration can either be only of the scrotum or also include the penis, known as a penectomy (often with a tube inserted to keep the urethra open, called a urethral rerouting). The practice was established before 700 BCE and accounts of eunuchs are known throughout history.

The English word eunuch is from the Greek eune ("bed") and ekhein ("to keep"), effectively "bed keeper". This indicates the traditional role of the eunuch - as a reliable keeper of a ruler's harem. Other servants or slaves were also castrated in order to make them 'safer', either in childhood or later.

In ancient China castration was both a traditional punishment (until the Sui Dynasty) and a means of gaining employment in the Imperial service. At the end of the Ming Dynasty there were 70,000 eunuchs (宦官 huàn'guān, or 太監 tàijiān) in the Imperial palace. The value of such employment - certain eunuchs gained immense power that may supersede that of the prime ministers -- was such that self-castration had to be made illegal. The number of eunuchs in Imperial employ had fallen to 470 in 1912, when the employment ceased.

Eunuchs were also known in India and throughout the East.

The practice was also well established in Europe among the Greeks and Romans, although only rarely for court functionaries as in Asia. In religion especially, followers of the goddess Cybele practiced ritual self-castration, sanguinaria. Even in Christian times the practice continued; as women were sometimes forbidden to sing in Church, their place was taken by castrati. The practice remained popular until the 18th century and was known into the 19th century, the last famous Italian castrato did not die until early in the 20th century.

The 18th-century Russian Skoptzy (скопцы) sect was an example of a castration cult, where its members regarded castration as a way of renouncing the sins of the flesh. Several members of the 20th century Heaven's Gate cult were found to have been castrated, apparently voluntarily and for the same reasons.

The body dysmorphic disorder or dysmorphophobia characterized by desire to be a eunuch is called skoptic syndrome, named after the Skoptzy sect. This desire is still present in modern populations, as evidenced in the large membership in message boards on the Internet related to the topic. There have also been frequent news coverage of incidents of self-castration (autocastration) and underground networks of people without medical licenses performing castrations. Most urologists have experience with patients who have attemped castration on themselves. According to a June 12 2002 article by Detroit Free Press: self-castrations tend to be more common than leaving the job to someone else, said Dr. Dana Ohl, a urologist at the U-M Medical Center who has operated on botched amateur castrations. "Usually, when these people just chop their own testicle off, they don't pay attention to the blood supply," he said.

See also: disfigurement, sexual reassignment surgery, female circumcision

Famous Chinese eunuchs

  • Cai Lun (lived around AD 105), conventionally regarded as the inventor of paper
  • Zhao Gao (died 210 BC)
  • Zheng He (1371-1435), mariner and explorer