Karel Halíř (1 February 1859 – 21 December 1909) was a Czech violinist who lived mainly in Germany. Karel is also seen as Karol, Karl or Carl; Halíř is also seen as Halir or Haliř.
Karel Halíř was born in Hohenelbe, Bohemia (now Vrchlabí, Czech Republic), and studied with Antonín Bennewitz in Prague and with Joseph Joachim in Berlin. He was leader in the orchestras at Königsberg (1879), Mannheim (1881) and Weimar (1884–94). His playing of the Bach Double Concerto with Joachim at the Bach Festival at Eisenach in 1884 was immensely successful. He became leader of the Berlin Court Opera and professor at the Hochschule für Musik.
Halíř toured the United States in 1896 and 1897. He was renowned for his playing of the Beethoven Violin Concerto in D major, and he played the work at his American debut on 13 November 1896, where it was described as "one of the most interesting and admirable pieces of violin playing that have been heard in New York". The performance was compared favourably to the previous performance of the work in New York by Eugène Ysaÿe, and the review concluded "To hear Herr Halir play ... is to understand what is meant by classical violin playing". On 4 December 1896 he gave the first performance in Carnegie Hall of Louis Spohr’s Violin Concerto No. 8, with the New York Symphony Orchestra conducted by Walter Damrosch. He joined the Joachim Quartet on his return to Berlin. He also led his own string quartet, to which Felix Weingartner’s String Quartet No. 1 was dedicated.