Bonanza: Under Attack is a 1995 made-for-television Western film. It is a sequel to the 1959–1973 television series Bonanza and television films Bonanza: The Next Generation (1988) and Bonanza: The Return (1993). The film was directed by Mark Tinker and features noted character actors Ben Johnson, Jack Elam (in his final appearance), and Richard Roundtree (reprising their roles from the 1993 film), as well as Leonard Nimoy and Dennis Farina.

The only leading actors from the original series who were still alive during production, Pernell Roberts and David Canary, do not appear in the film. However, the cast does include Michael Landon Jr. and Dirk Blocker, sons of the original series's actors who starred as Little Joe and Hoss Cartwright.

Nimoy and Farina portray real-life figures, outlaw Frank James (brother of Jesse James) and Pinkertons detective Charlie Siringo.