Final answer:
George Balanchine was the founder and director of the New York City Ballet from 1948 until 1983 and is considered one of the greatest choreographers of his time, known for his profound influence on ballet.
Step-by-step explanation:
The founder and director of the New York City Ballet from 1948 to his death in 1983, widely regarded as one of the greatest choreographers of his time, was George Balanchine. Balanchine's work had a significant impact on dance, and he is remembered for his genius in choreography and his lasting influence on ballet as an art form.
His tenure at the New York City Ballet was marked by a prolific output of works, innovation in dance technique, and collaborations with leading composers of his day, such as Igor Stravinsky, who composed the infamous 'The Rite of Spring'.