The South End is a neighborhood in Boston, Massachusetts, United States which is bordered by Back Bay, Chinatown, and Roxbury. It is distinguished from other neighborhoods by its Victorian-style houses and the parks in and around the area. The South End is the largest intact Victorian row-house district in the country, covering over 300 acres (120 ha). It has eleven residential parks. In 1973, the South End was listed on the National Register of Historic Places. Much of the neighborhood was originally marshlands in Boston's South Bay. After it was filled in, construction began on January 7, 1849.

It is home to diverse groups, including immigrants, young families and professionals, and it is popular with Boston's gay and lesbian community. The South End has been characterized by diversity since the 1880s, with substantial Irish, Jewish, African-American, Puerto Rican (in the San Juan Street area), Chinese, Italian, and Greek populations. Its 2010 population was 55.2 percent white, 13.3 percent Hispanic, 12.5 percent Black, 16.2 percent Asian, and 2.7 percent "other". 55.2 percent of South End residents had a bachelor's degree or higher; median household income was $57,699, and the median age was 36. 65.6 percent were primarily English speakers, and 12.9 percent primarily spoke Spanish.

The South End is south of the Back Bay, northwest of South Boston, northeast of Roxbury, north of Dorchester, and southwest of Bay Village. Despite the name, it is not directly south of downtown Boston.

Land belonging to the South End has been part of the city of Boston since its founding, although it was smaller when first settled and surrounded by large tidal flats. The neighborhood was expanded and developed by filling in the marshlands, part of a larger project of filling Boston's Back Bay and South Bay between the 1830s and the 1870s. Fill was brought in by train as gravel quarried in Needham. Nineteenth-century technology did not allow driving steel piles into bedrock, and a system of submerged timbers provided an understructure for most South End buildings. Groundwater levels in Boston had been dropping for years by 2006, damaging some wood pilings by exposing them to air. A series of monitoring wells have been drilled; the water level is checked by the Boston Groundwater Trust, and can be raised by introducing water.

The South End was bordered on the north and west by the Boston and Providence Railroad, which terminated at the B&PRR station bordering the Public Garden. The rail line is now covered by Southwest Corridor Park.

The primary business thoroughfares in the South End are Columbus Avenue, Tremont Street, and Washington Street. Washington Street, the original causeway that connected Roxbury to Boston, experienced reinvestment during the 1990s. The street was once defined by the Washington Street Elevated, an elevated train that was moved below Southwest Corridor Park in the 1980s. Part of the Silver Line, Boston's first bus rapid transit line, runs along Washington Street. The MBTA Orange Line rapid-transit train runs along the partially-covered Southwest Corridor.

The Boston Redevelopment Authority identified several subdistricts in the neighborhood's southeast portion:

The South End has eleven residential parks, varying in size and inspired by English-style residential squares first laid out downtown by Charles Bulfinch. The neighborhood also has newer parks, including Peters Park, and a series of sixteen community gardens and pocket parks operated by the Trustees of Reservations.