Satake and Miyazaki discussing the armor of thorns
According to the interview between Dark Souls' Director, Hidetaka Miyazaki, and Concept Artist, Daisuke Satake, found in Design Works artbook, the design of the Set of ThornsFW originated from the concept of the 77 Rings Challenge. In the challenge, combatants must defeat each other and wear the metal rings from each foe, increasing the weight they bear as they continue. The team's original idea was to use this design and try adding spikes to the rings, though it deviated along the way.
Just before the Iron Golem boss, you can summon a white phantom named Black Iron TarkusFW, which is likely a reference to Tarkus, as they share many similarities. They are both large powerful warriors who carry unwieldy weapons and thick armor, who both fall off a cliff in a similar fashion.
In Dark Souls II, you can encounter a boss called Executioner's ChariotFW. During the original network test prior to the games release, this boss instead had the name Silver Chariot, referencing the Stand of the same name from Part 3.
In Dark Souls III, a boss called
High Lord WolnirFW can be fought in the Catacombs of Carthus. He bears a striking resemblance to Enya Geil's Stand
Justice. He is a colossal skeleton wearing a crown, and even uses fog to attack and harm the players.