Penny (パティ Pati, known as "Patie" in the Japanese version and alternately "Patti" and "Patty") and Uri (ウルル Ururu, "Uluru") are a major enemy team during most of the Ancient Mamodo Arc of the manga, particularly due to Penny's own feelings towards Zatch. Penny's specialty is Water Magic.
Penny first appears looking for Zatch, pro-claiming to be his girlfriend. Zatch later discovers she actually fell for him in the Mamodo World. When he saw him fishing on her private beach, since she used all possible means to try to interact with him. Upon arriving at the Human World, Penny made a partnership with Uri, a poor man trying to get food for his family, the agreement had this condition: she would help him get food any way possible, since he helped find Zatch. Yet when she finally tracks Zatch down to Japan, Penny discovers the hard way about Zatch's lost memories, going absolutely berserk and forcing herself to fight him either to make him remember their (one-sided) love or to eliminate him from the tournament. Zatch proved his strength against Penny, but she is ultimately saved by the actions of Byonko moments before getting blasted by Zatch's Bao Zakeruga allowing Uri to escape with both of them. Her love for Zatch is so great that she wears panties with his face stamped on them.
After escaping, Penny meets with Byonko's boss, the evil Milordo-Z who offers her the chance to help him control the Ancient Mamodo and win the tournament. Seeing this as means to get revenge on Zatch, Penny takes the offer and leads a squadron of Ancient Mamodo into battle. But over time, she discovers her new servants lack the free will or abilities to fight for themselves and doubts the decisions she made. When Zatch and his allies appear hopeless fighting Demolt of the Four Supreme Mamodo, she and Byonko finally turn against their master, with Penny destroying the sustaining Moon Stone assisting the enemy with her So Giaku while getting her book burned. Her final wish while being sent back is for Zatch and the others to forgive and play with them when they return to the Mamodo world, which they agree to. Zatch also forgave Penny for her actions. In the King Festival Arc, through the power of the golden spellbook, Penny's spirit helped out Zatch and Kiyo to defeat Clear Note when Kiyo casted Shin So Giaku along with Byonko's Shin Nyushirudo.
Penny is last scene at school with Byonko, where she is "coincidentally" put in the same class as Zatch, whom she still retains feelings for. After the Ancient Mamodo Arc, Uri found employment as a chef in some restaurant and is only seen again when Zatch prepares to battle Clear, (which he is oblivious to) baking a cake in the shape of Penny's hairstyle (before she cut them off during her battle with Demolt), showing that he misses her very much.