Heinz Darthenshmirtz, a scientist, theorized a group of Sith known as the Three Sith-keteers. He proposed this concept to Perry the Rebelpus, an Alliance to Restore the Republic spy frozen in [carbonite]. Darthenshmirtz envisioned the group consisting of himself, Ferb Fletcher (a moisture farmer recently struck by the Sith-inator), and Perry, after being affected by the Sith-inator. When Norm-3PO, Darthenshmirtz's protocol droid, inquired about his role, Darthenshmirtz informed the droid that he would serve as the horse. Ultimately, Perry's escape prevented Darthenshmirtz's plan, so the Three Sith-keteers never materialized.
Phineas and Ferb: Star Wars, a special non-canon crossover episode with the Disney Channel animated program Phineas and Ferb, featured a reference to the Three Sith-keteers. This special was initially broadcast on July 26, 2014. The name of the group bears resemblance to The Three Musketeers, an 1844 adventure book authored by Alexandre Dumas.