Robert de Montesquiou was a scion of the French Montesquiou-Fézensac family.
His paternal grandfather was Count Anatole de Montesquiou-Fézensac (1788–1878), aide-de-camp to Napoleon and grand officer of the Légion d'honneur; his father was Anatole's third son, Thierry, who married Pauline Duroux, an orphan, in 1841.
With his wife's dowry, Thierry bought a Charnizay manor, built a mansion in Paris, and was elected Vice-President of the Jockey Club.
He was a successful stockbroker who left a substantial fortune.
Robert was the last of his parents' children, after brothers Gontran and Aymery, and sister Élise.
His cousin, Élisabeth, Countess Greffulhe (1860–1952), was one of Marcel Proust's models for the Duchess of Guermantes in À la recherche du temps perdu.

Montesquiou had a strong influence on Émile Gallé (1846–1904), a glass artist he collaborated with and commissioned major works from, and from whom he received hundreds of adulatory letters.
He also wrote the verses found in the optional choral parts of Gabriel Fauré's Pavane.

The portrait Arrangement in Black and Gold: Comte Robert de Montesquiou-Fezensac was painted in 1891–92 by Montesquiou's close friend, and model for many of his eccentric mannerisms, James Whistler.
The French artist Antonio de La Gandara (1861–1917) produced several portraits of Montesquiou.

One author provides the following verbal portrait of Montesquiou: "Tall, black-haired, Kaiser-moustached, he cackled and screamed in weird attitudes, giggling in high soprano, hiding his black teeth behind an exquisitely gloved hand—the poseur absolute.
Montesquiou's homosexual tendencies were patently obvious, but he may in fact have lived a chaste life.
He had no affairs with women, although in 1876 he reportedly once slept with the great actress Sarah Bernhardt, after which he vomited for twenty-four hours. (
She remained a great friend.)"

Montesquiou had social relationships and collaborations with many celebrities of the fin de siècle period, including Alphonse Daudet (1840–1897), Edmond de Goncourt (1822–1896), Eleonora Duse (1858–1924), Sarah Bernhardt (1844–1923), Gabriele d'Annunzio (1863–1938), Anna de Noailles (1876–1933), Marthe Bibesco (1886–1973), Luisa Casati (1881–1957), Maurice Barrès (1862–1923), and Franca Florio.

While Montesquiou had many aristocratic women friends, he much preferred the company of bright and attractive young men.
In 1885, he began a close long-term relationship with Gabriel Yturri (March 12, 1860 – July 6, 1905), a handsome South American immigrant from Tucuman, Argentina, who became his secretary, companion, and lover.
After Yturri died of diabetes, Henri Pinard replaced him as secretary in 1908 and eventually inherited Montesquiou's much reduced fortune.
Montesquiou and Yturri are buried alongside each other at Cimetière des Gonards in Versailles, Île-de-France, France.

A chronology of Montesquiou's life can be found at the website of the University of Napierville, Quebec.
Robert de Montesquiou was a scion of the French Montesquiou-Fézensac family. His paternal grandfather was Count Anatole de Montesquiou-Fézensac (1788–1878), aide-de-camp to Napoleon and grand officer of the Légion d'honneur; his father was Anatole's third son, Thierry, who married Pauline Duroux, an orphan, in 1841. With his wife's dowry, Thierry bought a Charnizay manor, built a mansion in Paris, and was elected Vice-President of the Jockey Club. He was a successful stockbroker who left a substantial fortune. Robert was the last of his parents' children, after brothers Gontran and Aymery, and sister Élise. His cousin, Élisabeth, Countess Greffulhe (1860–1952), was one of Marcel Proust's models for the Duchess of Guermantes in À la recherche du temps perdu.
Montesquiou had a strong influence on Émile Gallé (1846–1904), a glass artist he collaborated with and commissioned major works from, and from whom he received hundreds of adulatory letters. He also wrote the verses found in the optional choral parts of Gabriel Fauré's Pavane.
The portrait Arrangement in Black and Gold: Comte Robert de Montesquiou-Fezensac was painted in 1891–92 by Montesquiou's close friend, and model for many of his eccentric mannerisms, James Whistler. The French artist Antonio de La Gandara (1861–1917) produced several portraits of Montesquiou.
One author provides the following verbal portrait of Montesquiou: "Tall, black-haired, Kaiser-moustached, he cackled and screamed in weird attitudes, giggling in high soprano, hiding his black teeth behind an exquisitely gloved hand—the poseur absolute. Montesquiou's homosexual tendencies were patently obvious, but he may in fact have lived a chaste life. He had no affairs with women, although in 1876 he reportedly once slept with the great actress Sarah Bernhardt, after which he vomited for twenty-four hours. (She remained a great friend.)"
Montesquiou had social relationships and collaborations with many celebrities of the fin de siècle period, including Alphonse Daudet (1840–1897), Edmond de Goncourt (1822–1896), Eleonora Duse (1858–1924), Sarah Bernhardt (1844–1923), Gabriele d'Annunzio (1863–1938), Anna de Noailles (1876–1933), Marthe Bibesco (1886–1973), Luisa Casati (1881–1957), Maurice Barrès (1862–1923), and Franca Florio.
While Montesquiou had many aristocratic women friends, he much preferred the company of bright and attractive young men. In 1885, he began a close long-term relationship with Gabriel Yturri (March 12, 1860 – July 6, 1905), a handsome South American immigrant from Tucuman, Argentina, who became his secretary, companion, and lover. After Yturri died of diabetes, Henri Pinard replaced him as secretary in 1908 and eventually inherited Montesquiou's much reduced fortune. Montesquiou and Yturri are buried alongside each other at Cimetière des Gonards in Versailles, Île-de-France, France.
A chronology of Montesquiou's life can be found at the website of the University of Napierville, Quebec.
Robert de Montesquiou