Diego Salamanda is the arch-enemy of the Gatekeepers in the second and third books of The Power of Five and is Matt's enemy for much of the series.
Diego Salamanda controls a large business corporation in Peru, named Salamanda News International (Richard Cole says he should just call it Salamanda International News, which would spell SIN) which some say controls Peru. Salamanda himself is the chairman. He is one of the richest men in South America, and "certainly the richest man in Peru."
Diego Salamanda has contacts round the world and he is a board member of the Nightrise Corporation, a corporation of fascist fanatics who want to free the Old Ones. He learned that he needed a special diary to free the Old Ones, a diary written by a fourteenth-century man named Saint Joseph from Cordoba, who predicted many future inventions such as technology. Salamanda learned that the diary was being auctioned in London, England, and he sent an assassin in his company to track down the seller, a man named William Morton, and kill him, and steal the diary. Salamanda knew of the Five Gatekeepers and he said that if Matt was there, the assassin could kill him, but if he wasn't, ignore him. Matt had taken a portal (disguised as a normal church door) into a cathedral in Italy, so he was safe from Salamanda when he did kill Morton.
Later on, the Nexus corporation realized the diary had been stolen and they tracked down Salamanda and sent Matt after him. Matt went to Peru but immediately things went wrong when him and Richard were attacked by Peruvian men, (later revealed as Incas) and Richard was kidnapped, but then Matt escaped and met a boy named Pedro who turned out to be the second of the Five, a Gatekeeper like Matt, and Matt and Pedro went to meet Salamanda and ask him if Richard was there.
Salamanda, when they got to him, was revealed to be deformed - he had a gigantic head, because he was the product of an experiment by Peruvians that shrunk the head between two wooden boards and was meant to be a gift from the gods. But Salamanda appreciated his "gift" because even though it meant he looked hideous, ("a child's head in an adult's body") he understood he was special, so he thought, because he was going to free the Old Ones.
Salamanda denied he had Richard and said that he knew the Gatekeepers were there because he felt their presence. Then he got his men to hunt them down and kill them, but Matt and Pedro escaped thanks to an Inca, but when he told them to go to Cuzco, he was shot dead by the guards, and Matt and Pedro had to run.
His agent revealed
In Cuzco, Matt phoned Fabian, a man from the Nexus, who lived in Peru, and then, Fabian phoned Salamanda, because Fabian was a traitor with the Old Ones. He betrayed Matt to Salamanda but again the Incas rescued Matt and Pedro. They took them to their headquarters, and later, Matt and Pedro worked out Salamanda's goal, to bring the Old Ones back by opening the gate in the Nazca Desert, over the Nazca Lines, and then they went to Salamanda to stop him. Matt confronted Salamanda in the desert, and Salamanda demanded to know how Matt was still alive. Matt asked Salamanda the time, and Salamanda was shocked. But he understood, and said it was five minutes to midnight because then the Old Ones would soon be free and he said he hated Matt for constantly evading him, and Matt said hate was all Salamanda knew, and Salamanda shot at Matt. However, Matt used his powers to throw the bullets back at Salamanda, and they hit him, and then he was thrown off his feet, his neck broken.
But his scheme was successful; the gate opened (Matt realized it was the whole Nazca Desert too late) and the Old Ones and their lord Chaos came out and challenged Matt.
- Anthony Horowitz has said that because the alien like figure on the Nazca Lines was "Definitely not E.T.", this strongly suggests the figure was probably meant to represent Salamanda himself.