Final answer:
Theodore Thomas is a famous immigrant musician who played violin with the New York Philharmonic and founded his professional orchestra.
Step-by-step explanation:
The famous immigrant musician who played violin with the New York Philharmonic and founded his professional orchestra in 1865 is Theodore Thomas.
He was a German-born violinist and conductor who promoted classical masterworks and introduced the concept of outdoor concerts that interspersed dances and lighter music, which is still popular today. He promoted classical masterworks and introduced the concept of outdoor concerts.