Carl Otto Ehrenfried Nicolai (9 June 1810 – 11 May 1849) was a German composer, conductor, and founder of the Vienna Philharmonic. Nicolai is best known for his operatic version of Shakespeare's comedy The Merry Wives of Windsor (Die lustigen Weiber von Windsor). In addition to five operas, Nicolai composed lieder, works for orchestra, chorus, ensemble, and solo instruments.

Nicolai, a child prodigy, was born in Königsberg, Prussia. He received his first musical education from his father, himself a composer and musical director, Carl Ernst Daniel Nicolai. During his childhood his parents divorced, and while still a youth, early in June 1826, Nicolai ran away from his parents' "loveless" home,[1] taking refuge in Stargard with a senior legal official called August Adler who treated the musical prodigy like a son and, when Nikolai was seventeen, sent him to Berlin to study with Carl Friedrich Zelter.

After initial successes in Germany, including his first Symphony (1831) and public concerts, he became musician to the Prussian Embassy in Rome. During the early 1840s he established himself as a major figure in the concert life of Vienna. In 1844 he was offered the position, vacated by Felix Mendelssohn, of Kapellmeister at the Berlin Cathedral; but he did not reestablish himself in Berlin until the last year of his life. On 11 May 1849, two months after the premiere of The Merry Wives of Windsor, and only two days after his appointment as Hofkapellmeister at the Berlin Staatsoper, he collapsed and died from a stroke. On the very same day of his death, he was elected a member of the Royal Prussian Academy of Arts.