Nikolay Aleksandrovich Lvov (Russian: Николай Александрович Львов; May 4, 1753 – December 21, 1803) was a Russian artist of the Age of Enlightenment. Lvov, an amateur of noble lineage, was a polymath who contributed to geology, history, graphic arts and poetry, but is known primarily as an architect and ethnographer, compiler of the first significant collection of Russian folk songs (the Lvov-Prach collection).

Lvov's architecture represented the second, "strict" generation of neoclassicism stylistically close to Giacomo Quarenghi. Lvov worked in Saint Petersburg but his best works survived in the countryside, especially his native Tver Governorate. He redesigned the external appearance of Peter and Paul Fortress and created an unprecedented Trinity Church combining a Roman rotunda with one-of-a-kind pyramidal bell tower. He adapted rammed earth technology to the environment of Northern Russia and used it in his extant Priory Palace in Gatchina; Lvov's construction school, established in 1797, trained over 800 craftsmen. He managed geological surveys and published a treatise on the coals from Donets Basin and Moscow Basin. He experimented with coal pyrolysis, proposed new uses for coal tar and sulphur, and wrote a reference book on heating and ventilation.

Lvov designed the badges of the Order of St. Vladimir and the Order of St. Anna, translated works by Anacreon, Palladio, Petrarch, Sappho and the Saga of King Harald into Russian language, wrote libretto for opera and vaudeville, researched Russian chronicles and published one of the first versions of the bylina of Dobrynya Nikitich. In 1783, he became one of the first 36 members of the Russian Academy.

In 1931, Vladislav Khodasevich called Lvov "an intelligent and subtle connoisseur of everything ... who was not destined to do anything remarkable." Later researchers appreciated Lvov's contribution: Richard Taruskin considered Lvov's collection of folk songs "the greatest and most culturally significant of Russian folk collections", Philip Bohlman credited discovery of Russian folk art "all from the actions of a single individual, Lvov", William Craft Brumfield called Lvov "one of the greatest neoclassical architects produced in the reign of Catherine the Great... neoclassical aesthetics at its purest".

Nikolay Lvov was born in an impoverished country estate 16 kilometres (9.9 mi) from Torzhok. Sources published before 2001 state date of birth March 4, 1751; in 2001, Galina Dmitrieva published newly found church records showing that Lvov was actually born May 4, 1753.

In line with tradition, his parents "enrolled" Nikolay into Preobrazhensky Lifeguard regiment in 1759. Ten years later, Nikolay arrived in Saint Petersburg and joined the regiment. In 1770–1771, he attended training courses at Izmaylovsky Regiment; these courses were the only instance of formal education in his life. Until 1775, Lvov, along with his military service that became a mere formality, was also employed by the Collegium of Foreign Affairs as a diplomatic courier and extensively travelled to German principalities and Denmark. In July 1775, Lvov resigned both military and civil service in the rank of captain and returned to his parents' estate, but one year later returned to diplomatic service. This time, he travelled to London, Madrid, Paris and the Netherlands; in Paris, Lvov indulged in frequent theatre going and made good acquaintance with poet Ivan Khemnitser and the Bakunin family.

Back in Saint Petersburg, Lvov created a private theatre based in the Bakunin house and played lead parts in plays by Jean-François Regnard, Antonio Sacchini and, probably, Yakov Knyazhnin. He led otherwise a modest lifestyle of a salaried clerk, living at his friends' houses, and could not afford renting his own until May 1779, when his pay was raised to 700 roubles per annum.

Around 1778 or 1779, Lvov developed relationship with Maria Dyakova (her sister Alexandra was engaged to Vasily Kapnist). Maria's father, an influential statesman, distrusted Lvov at first sight and ruled out any marriage proposals. She and Lvov were secretly married in a church in Saint Petersburg on November 8, 1780. Maria still lived in her parents' house for three more years. By 1783, Lvov's social standing improved to the point where the father reluctantly approved the marriage; only then the secret ceremony of 1780 became public. The affair between Lvov and Maria Dyakova became a subject of romance novel fiction (the most recent paperback was issued in 2008).