Sunset Boulevard is a boulevard in the central and western part of Los Angeles, California, United States, that stretches from the Pacific Coast Highway in Pacific Palisades east to Figueroa Street in Downtown Los Angeles. It is a major thoroughfare in the cities of Beverly Hills and West Hollywood (including a portion known as the Sunset Strip), as well as several districts in Los Angeles.

Approximately 23.6 miles (38 km) in length, the boulevard roughly traces the arc of mountains that form part of the northern boundary of the Los Angeles Basin, following the path of a 1780s cattle trail from the Pueblo de Los Angeles to the ocean.

From Downtown Los Angeles, the boulevard heads northwest, to Hollywood, through which it travels due west for several miles before it bends southwest towards the ocean. It passes through or near Echo Park, Silver Lake, Los Feliz, Hollywood, West Hollywood, Beverly Hills, and Holmby Hills. In Bel-Air, Sunset Boulevard runs along the northern boundary of UCLA's Westwood campus. The boulevard continues through Brentwood to Pacific Palisades, where it terminates at the Pacific Coast Highway intersection.

The boulevard has curvaceous winding stretches, and can be treacherous for unalert drivers in some sections. Sunset Boulevard is at least four lanes wide along its entire route. Sunset is frequently congested with traffic loads beyond its design capacity.

Sunset Boulevard historically extended farther east than it does now, starting at Alameda Street near Union Station and beside Olvera Street in the historic section of Downtown. The portion of Sunset Boulevard east of Figueroa Street was renamed Cesar Chavez Avenue in 1994, along with Macy Street and Brooklyn Avenue, in honor of the late Mexican-American union leader and civil rights activist.

In 1877, Harvey Henderson Wilcox, one of the earlier real estate owners from "back East", decided to subdivide more than 20 acres (8.1 ha) of land (mostly orchards and vineyards) along Sunset Boulevard, including what is today Hollywood and Vine.

In 1890, Belgian diplomat Victor Ponet bought 240 acres (97 ha) of the former Rancho La Brea land grant. His son-in-law, Francis S. Montgomery, inherited this property and created Sunset Plaza.

According to a 1901 article in the Los Angeles Herald, Sunset only extended from Hollywood in the west to Marion Avenue in the Echo Park district in the east. The Board of Public Works proposed to extend Sunset east to Main Street in the Plaza by routing the road over the existing section of Bellevue Avenue, but the plan was delayed until approximately 1904, due to active opposition by affected land owners. According to the 1910 Baist Real Estate Survey Atlas, Sunset Boulevard reached the Plaza by that time, but it did so by two short and narrow segments which were not aligned with each other and thus did not provide a proper thoroughfare to it. In late 1912, several properties along the route were condemned so that the boulevard could be changed in both its width and its alignment. With these changes completed, Sunset Boulevard now reached North Main Street and continued as Marchessault along the northern end of the Plaza. This section, variously marked and signed as Marchessault Street or East Sunset Boulevard, remained open to traffic until the late 1960s or early 1970s. At that time, Sunset was realigned one block north and Marchessault was closed to motor traffic.

In 1921 a westward expansion of Sunset began, extending the road from the then-current terminus at Sullivan Canyon toward the coast. This land, a portion of the original 1838 holdings of Francisco Marquez, stretched across a mesa and became known as the "Riviera section". Will Rogers, who had bought much of this land as an investment, later donated it to the State of California creating Will Rogers State Historic Park. c. 1931, Sunset was a paved road from Horn Avenue to Havenhurst Avenue.

The Sunset Strip portion of Sunset Boulevard in West Hollywood has been famous for its active nightlife since at least the 1950s.

In contrast to other American cities where it referred to a concentration of radio retailers, in Los Angeles, Radio Row was understood in the 1940s–1950s as the area around the intersection of Sunset Boulevard and Vine Street in Hollywood, where the broadcasting facilities of all four major radio networks were located.

In the 1970s, the area between Gardner Street and Western Avenue was a center for street prostitution. Shortly after a much publicized incident in late June 1995, police raids drove out the majority of prostitutes on the Boulevard.

Part of Sunset Boulevard in Hollywood is also sometimes called "Guitar Row" due to the large number of guitar stores and music industry-related businesses, including the recording studios Sunset Sound Studios and United Western Recorders.

The portion of Sunset Boulevard that passes through Beverly Hills was once named Beverly Boulevard.

The boulevard is commemorated in Billy Wilder's film Sunset Boulevard (1950), the Andrew Lloyd Webber musical of the same name, and the 1950s television series 77 Sunset Strip. Jan and Dean's 1960s hit song "Dead Man's Curve" refers to a section of the road near Bel Air estates just north of UCLA's Drake Stadium where Jan Berry almost died in an automobile accident in 1966. The Buffalo Springfield song "For What It's Worth" was written about a riot at Pandora's Box, a Sunset Strip club, in 1966.

Metro Local lines 2, 4 and 602 operate on Sunset Boulevard, with Line 2 running through most of Sunset Boulevard between Echo Park and UCLA, Line 4 between Sunset Junction and Downtown LA, and Line 602 from UCLA west. The Metro B Line operates a subway station at Vermont Avenue.

At 4334 W. Sunset Boulevard lies the wall featured on the cover of the late singer-songwriter Elliott Smith's 2000 album Figure 8. Since Smith's death in 2003, the wall has become a memorial for the artist; fans have left many personal messages there over the years.

• Sunset Boulevard (film) (1950)

• Libman, Gary (December 18, 1988). "Street of Contrasts in a Changing L.A. : Sunset Boulevard: Epitome of L.A. : As It Winds From Plaza to Ocean, Diversity Is Its Name". Los Angeles Times.