Simeon Stylites or Symeon the Stylite (Greek: Συμεών ό Στυλίτης; Syriac: ܫܡܥܘܢ ܕܐܣܛܘܢܐ, romanized: Šimʕun dʼAstˁonā; Arabic: سمعان العمودي, romanized: Simʿān al-ʿAmūdī c. 390 – 2 September 459) was a Syrian Christian ascetic, who achieved notability by living 36 years on a small platform on top of a pillar near Aleppo (in modern Syria). Several other stylites later followed his model (the Greek word style means "pillar"). Simeon is venerated as a saint by the Eastern Catholic Churches, Oriental Orthodox Churches, Eastern Orthodox Church, and Roman Catholic Church. He is known formally as Simeon Stylites the Elder to distinguish him from Simeon Stylites the Younger, Simeon Stylites III and Symeon Stylites of Lesbos.

There exist three major early biographies of Simeon. The first of these is by Theodoret, bishop of Cyrrhus, and is found within his work Religious History. This biography was written during Simeon's lifetime, and Theodoret relates several events of which he claims to be an eyewitness. The narrator of a second biography names himself as Antonius, a disciple of Simeon's. This work is of unknown date and provenance. The third is a Syriac source, which dates to 473. This is the longest of the three, and the most effusive in its praise of Simeon; it places Simeon on a par with the Old Testament prophets, and portrays him as a founder of the Christian Church. The three sources exhibit signs of independent development; although they each follow the same rough outline, they have hardly any narrative episodes in common.

All three sources have been translated into English by Robert Doran. The Syriac life has also been translated by Frederick Lent.

The traditional consensus is that Simeon Stylites adhered to Chalcedonian Christianity, with Syriac letters claiming that he was a Monophysite being viewed as forgeries.

The son of a shepherd, Simeon was born and raised in Sis, which was then a part of the Eastern Roman province of Cilicia. According to Theodoret, Simeon developed a zeal for Christianity at the age of 13, following a reading of the Beatitudes. He entered a monastery before the age of 16. From the first day, he gave himself up to the practice of an austerity so extreme that his brethren judged him to be unsuited to any form of community life. They asked Simeon to leave the monastery.^{[citation needed]}

Simeon shut himself up in a hut for one and a half years, where he passed the whole of Lent without eating or drinking. When he emerged from the hut, his achievement was hailed as a miracle. He later took to standing continually upright so long as his limbs would sustain him.^{[citation needed]}

After one and a half years in his hut, Simeon sought a rocky eminence on the slopes of what is now the Sheik Barakat Mountain, part of Mount Simeon. He chose to live within a narrow space, less than 20 meters (66 ft) in diameter. But crowds of pilgrims invaded the area to seek him out, asking his counsel or his prayers, and leaving him insufficient time for his own devotions. This eventually led him to adopt a new way of life.

In order to get away from the ever-increasing number of people who came to him for prayers and advice, leaving him little if any time for his private austerities, Simeon discovered a pillar which had survived among ruins in nearby Telanissa (modern-day Taladah in Syria).