Mantis Undead

Given the name the "Legendary Heart Warrior", the Mantis Undead is the best fighter of all the Undead. As such, Dirk Trent uses the Undead's form & assumes the identity of "Kamen Rider Heart Warrior" while suppressing his Joker nature. (Technically, the form of the Undead is how the Rider form appears save for an Undead belt (while the Rider has the Heart Rouzer)), as noted by the Eagle Undead before Kamen Rider Spade Warrior sealed him.) Though Club Warrior unseals the Mantis Undead, he is resealed by the Black Joker.