This article discusses the television program. For the airplane see Beechcraft Bonanza.

Bonanza was an American western/cowboy television program starring Lorne Greene, Michael Landon, Dan Blocker, Pernell Roberts, and Victor Sen Yung. It was the first regularly broadcast television program to be filmed in color.

It aired on NBC from September 12, 1959 through January 16, 1973; from 1961 to 1972 it aired on Sunday nights. This timeslot was crucial to the success of the show: from 1964 until 1967, the show was #1 in the yearly Nielsen ratings. In terms of longevity, the show was the second-most popular western in the history of television, behind Gunsmoke.

Ponderosa was an alternative title of the series, often used for the broadcast of syndicated reruns in the 1970s and 1980s.

The show chronicled the weekly adventures of the Cartwright family, headed by patriarch Ben Cartwright (Greene). He had three sons: Joseph or "Little Joe" (Landon); Adam (Roberts); and Eric, better known to viewers by his nickname of "Hoss" (Blocker). The family's cook was the Chinese immigrant Hop Sing (Sen Yung). The family lived on a ranch called "The Ponderosa", on the shore of Lake Tahoe in Nevada; the name refers to the Ponderosa Pine, common in the West. The nearest town to the Ponderosa was Virginia City, where the Cartwrights would go converse with Sheriff Roy Coffee (played by veteran actor Ray Teal ).

The cast was very popular with viewers, and Lorne Greene recorded several record albums in character as Ben Cartwright, scoring a top-10 hit with his dramatic spoken word performance of "Ringo".

The show slowly lost its original format when Pernell Roberts left the series in 1965 for a movie career. The show was still highly rated with just two Cartwright brothers, but it slowly dropped out of the number-one spot that it held for so long. In 1972, after the sudden death of Dan Blocker, the show was moved to Tuesday nights. Both moves signaled the end of the program, and it went off the air quietly early the next year.

For fourteen years the Cartwrights were the premier western family on American television and are still immensely popular on networks such as TV Land and Hallmark.

Following the program's cancellation it was brought back as several made-for-television movies. These include Bonanza: The Movie (1988), Back to Bonanza (1993), Bonanza: The Return (1993), Bonanza: Under Attack (1995), and Bonanza: The Next Generation (1995).

In 2001, there was an attempt to revive the series' ideas with a prequel, Ponderosa, with a pilot directed by Kevin James Dobson and filmed in Australia. Covering the time when the Cartwrights first arrived at the Ponderosa, it lasted 20 episodes.

Bonanza also featured a memorable theme song that is often parodied. Lorne Greene and the cast recorded versions of the song with lyrics. Although the Bonanza theme is one of the best known pieces of made-for-television music, it was not used for the entire run of the series.