Kamen Rider 555 (Faiz) (仮面ライダー５５５ファイズ, Kamen Raidā Faizu, Masked Rider Φ's) is a Japanese tokusatsu drama and the 17th installment of the Kamen Rider Series. Debuting as the fourth entry of the Heisei Era, the series premiered on January 26, 2003 alongside Bakuryu Sentai AbarangerIcon-crosswiki on TV Asahi's Super Hero Time block, and ended its 50-episode run on January 18, 2004.

The Smart Brain corporation, the world's most powerful corporation, is trying to take over the world using Orphnoch, the next stage in humanity's evolution, to covertly kill off the human population. In pursuit of this, they develop three suits of power armor, called Rider Gear (Delta, Faiz, and Kaixa), to find and protect the Orphnoch King, who can fix a defect within Orphnoch DNA which causes their genetic structure to break down, leading to death.