Yannis Costantinidis (Γιάννης Κωνσταντινίδης), also known by the penname Kostas Giannidis (Greek: Κώστας Γιαννίδης) (21 August 1903 – 17 January 1984) was a Greek composer, pianist and conductor. Giannidis was born in Smyrna in 1903. He came to Greece after the destruction of Smyrna and continued his studies in Berlin (1923–1931). He returned to Athens and worked as a conductor and composer at the musical theatre composing many operettas, musical comedies and revues. He died in Athens.