Grimsley Senior High School (also known as Grimsley High School or simply Grimsley) is a four-year public high school in Greensboro, North Carolina, United States. Formerly known as "Greensboro High School", "Greensboro Central High School", and then "Greensboro Senior High School", it is part of the Guilford County Schools system. The school has an enrollment of around 1,900 students in grades 9–12. The school's colors are navy blue and white, and its teams are known as the "Whirlies" (originally the "Purple Whirlwind") depicted with a tornado-like symbol.

Established in 1899, Grimsley is the oldest institution of public secondary education in Greensboro and Guilford County, and is one of the oldest high schools in the state. The school campus was listed on the National Register of Historic Places in 2005.

GHS was founded in 1899 as Greensboro High School; it became Greensboro Central High School in 1911 and Greensboro Senior High School in 1929 (when it moved to its current campus, after previously having had two locations in downtown Greensboro). In 1962, it was renamed Grimsley Senior High School in honor of George Adonijah Grimsley (1862–1935), an educator, insurance executive, and superintendent of Greensboro's schools, who fostered the establishment of the high school in 1899.

Upon its establishment in the fall of 1899, Greensboro High School was located on North Forbis Street in the former St. Agnes Catholic building, on part of the site of the current Greensboro Public Library, behind the Greensboro Historical Museum. By 1910, this building was outgrown, so for one year (1910–1911) GHS was moved next door to the Lindsay Street Grammar School. In the fall of 1911, the school moved to the site of today's Weaver Academy, where it became Greensboro Central High School, and where it remained until 1929. In the fall of 1929, GHS moved to its current Westover Terrace location, when it became Greensboro Senior High School. See "facilities" section below for a description of the current campus.

In 1902, Greensboro High School established the first school library and book rental system in the state. 10th grade was also added that year (previously 9th grade was the highest grade). In 1911, after the move to Spring Street, 11th grade was added.

In 1934, as part of the New Deal's Civil Works Administration (CWA), two large murals were painted in the GHS auditorium by Raleigh artist James A. McLean: "Energy" and "Education".

The school's original colors were purple and gold (circa 1909–10). Because of increasing difficulty in finding matching shades of purple for athletic and band uniforms, the colors were changed—by vote of the student body in March 1951—to navy blue and white.

The mascot was originally the "Purple Whirlwind", adopted in 1921. Local papers, in an attempt to have variety when referring to GHS's teams (and to save space in headlines) came up with the name "Whirlies" in 1941. (Other variations of "Purple Whirlwinds" had been used back to the 1930s.) The name "Whirlies" caught on quickly and was used interchangeably with "Purple Whirlwinds" until the color change in 1951, leaving the original mascot name as "Whirlwinds". Since the late 1950s, "Whirlies" has been used almost exclusively.