William Aloysius Shine Great Neck South High School (commonly Great Neck South, South High School, or GNSHS) is a four-year public high school located in the Village of Lake Success, New York, on the bottom of the Great Neck Peninsula. The school serves students in grades 9 through 12 residing within the Great Neck School District.

Great Neck South is one of three public high schools in the Great Neck school district, alongside Great Neck North High School and Great Neck Village High School. Great Neck South offers its students academic acceleration, along with special education classes for students with disabilities. The school opened in 1958 and was named Great Neck South High School until 2006.

As of the 2023-2024 school year, the school had an enrollment of 1,322 students and 117.61 classroom teachers, on an FTE scale, for a student–teacher ratio of 11.24:1. In the same academic year, 276 students were eligible for free lunch and 27 were eligible for a reduced-cost lunch.