Egregore (also egregor) is an occult concept representing a "thoughtform" or "collective group mind", an autonomous psychic entity made up of, and influencing, the thoughts of a group of people. The symbiotic relationship between an egregore and its group has been compared to the more recent, non-occult concepts of the corporation (as a legal entity) and the meme.
The first author to adapt "egregore" in a modern language seems to be the French poet Victor Hugo, in La Légende des Siècles ("The Legend of the Ages"), First Series, 1859, where he uses the word "égrégore" first as an adjective, then as a noun, while leaving the meaning obscure. The author seems to have needed a word rhyming with words ending in the sound "or". It would not be the only example of word creation by Victor Hugo. However, the word is the normal form that the Greek word ἑγρήγορος (Watcher) would take in French. This was the term used in the Book of Enoch for great angel-like spirits.
Eliphas Lévi, in Le Grand Arcane ("The Great Mystery", 1868) identifies "egregors" with the tradition concerning the "Watchers", the fathers of the nephilim, describing them as "terrible beings" that "crush us without pity because they are unaware of our existence."
The concept has enjoyed renewed popularity among practitioners of chaos magic, following the Corporate Metabolism series of articles by Paco Xander Nathan, which were published in 2001.
The result of a synergy of thought could be the most concise description of this state of mind.
The notion of "egregor" also appears in Daniil Andreyev's Roza Mira, where it represents the shining cloud-like spirit associated with the Church. It is a common belief in Russia that the word "egregor" originated from this spiritual book.
The Russian occult movement DEIR, led by Dmitry Verischchagin, also employs this concept.
The protagonist of the 1970 novel "Be Not Content" (about the early days of LSD) is named "Abel Egregore." 
- Victor Hugo, "Le jour des rois", La Légende des Siècles IV, V, and "L'Italie – Ratbert", La Légende des Siècles VII. Both in the Première Série, 1859.
- Lévi, Eliphas, "The Great Mystery" (1868) p.127-130, 133, 136
- Fama Fraternitatis Rosae Crucis.(1614) Manifesto: Positio. Epilogue page 25
- Flowers (1995), p. 36-38
- Delaforge, Gaeten, "The Templar Tradition: Yesterday and Today", Gnosis Magazine, #6, 1987.
- Ellenwood, Ray, Egregore : a history of the Montréal automatist movement. Toronto: Exile Editions, 1992. ISBN 9781550960211
- Craddock, William J., Be Not Content (A Subterranean Journal). Los Gatos California: Transreal Books, 2012. ISBN 9780984758531
- Bernstein, L.S. (1998). "Egregor". The Rosicrucian Archive. Confraternity of the Rose Cross. Retrieved November 22, 2011.
- Butler, Walter Ernest (1970). "The Egregore of a School". Servantsofthelight.org. The Servants of the Light. Retrieved November 22, 2011.
- Flowers, S. Edred (1995). Fire & Ice: Magical Teachings of Germany's Greatest Secret Occult Order. Llewellyn's Teutonic Magick Series (2nd ed.). Llewellyn Publications. ISBN 0-87542-776-6.
- Nathan, Paco Xander (2001). "Chasing Egregors". The Scarlet Letter (Scarlet Woman Lodge, Ordo Templi Orientis) VI (1).