Six Flags Magic Mountain, formerly known and colloquially referred to as simply Magic Mountain, is a 209-acre (85 ha) amusement park located in Valencia, California, 35 miles (56 km) northwest of downtown Los Angeles. It opened on May 29, 1971, as a development of the Newhall Land and Farming Company and Sea World Inc. In 1979, Six Flags purchased the park and added "Six Flags" to the park's name.

With 19 roller coasters, Six Flags Magic Mountain holds the world record for most roller coasters in an amusement park. It became the first amusement park to offer 20 roller coasters with the opening of Wonder Woman: Flight of Courage in 2022. It previously offered 20 roller coasters before the 2019 removal of Green Lantern: First Flight. It again offered 20 roller coasters before the 2025 removal of Superman: Escape from Krypton. In 2024, the park had an estimated 3.31 million visitors, ranking it 16th in attendance in North America.

In 1968, Sea World Inc. founder George Millay and his executives began looking for a place in Los Angeles county to build a theme park. Knowing that Newhall Land and Farming Company had enough undeveloped land in the new town of Valencia, he asked CEO John F. Dickason if they could build on his land. They eventually formed a partnership to build a 200-acre theme park. Construction began in November 1969 and continued until May 1971. The park was named after the nearby Magic Mountain, a peak located to the east of the Santa Clarita Valley.

When the park opened, there were 500 employees and 33 attractions, many of which were designed and built by Arrow Development, which had previously worked on attractions at Disneyland. The admission price in 1971 was $5 for adults, and $3.50 for children between the ages of 3 and 12. Because the park was in a relatively remote part of Los Angeles County at the time, the Greyhound bus line provided bus service to and from the park and Los Angeles, and from Northern California, and optionally allowed purchase of park admission at the time the bus ticket was purchased.

At its 1971 opening, the rides and attractions included Gold Rusher, a steel coaster; the Log Jammer, a log flume; the Sky Tower, an observation tower; Grand Prix, similar to Disneyland's Autopia ride; El Bumpo, bumper boats; a carousel; and other smaller rides. There were four transportation rides to the peak: Funicular, a cable railway or funicular, which was renamed Orient Express, then Helpful Honda Express, and is currently named Magic Mover.

Attractions included The Metro, which was three monorail stations around the park, including the Whitewater Lake, Country Fair, and Mountain stations; and "Eagles Flight", a gondola lift ride that had two stations at the peak, the long one north to Galaxy Station and the short one west to El Dorado Station. The Showcase Theater (later renamed the Golden Bear Theater) was part of the original park and featured Barbra Streisand as the first of many headline performers who would appear at Magic Mountain over the years.

In the 1971 season, Magic Mountain obtained permission from Warner Bros. to use Looney Tunes/Merrie Melodies characters. They did not continue using the characters after their first year. Six Flags Great America, has continuously used such characters since its opening in 1976, eight years before Marriott Corporation sold the park to Six Flags.

In 1972, Magic Mountain began using trolls as the park mascots. The trolls King Blop, also known as King Troll, Bleep, Bloop, and the Wizard became recognizable symbols of Magic Mountain. All King Productions, a contractor, provided the entertainers wearing the costumes until December 31, 1972, when Magic Mountain took on that role. The characters were used until 1985. Also in 1972, a second flume ride named Jet Stream was added.