Here's a brief guide to every skull shown in Predator 2's trophy room. While Predator became a huge hit in 1987 it suffered through a troubled production. A key issue was the design of the title creature, which was originally an insectoid looking alien played by Jean-Claude Van Damme. In addition to the suit being almost impossible to work in - with Van Damme passing out several times due to the heat - the design itself was famously awful. The decision was made to scrap this outfit and Stan Winston was brought on to build a new suit. This created one of sci-fi cinemas most enduring creatures and the movie's success led to a sequel being greenlit.
Arnold Schwarzenegger passed on Predator 2 as he disliked the idea of the hunter in a city. Instead, Danny Glover (Lethal Weapon) was cast as the new hero, a cop trying to solve a string of brutal murders during a Los Angeles heatwave - naturally, the problem is extraterrestrial. The sequel received mixed reviews and was a box-office disappointment, though it's been reappraised as an enjoyable follow-up in recent years. The movie was also referenced in 2018's The Predator with Sean Keyes, the son of Predator 2's deceased agent Peter Keyes, continuing his father's work studying the hunters; Sean is even played by Jake Busey, the real-life son of Peter Keyes performer Gary Busey.
Predator director John McTiernan - who also helmed Die Hard - cut out a number of sequences from the original script, including Schwarzenegger's character finding a cloaked Predator ship filled with human trophies. This concept was revised for Predator 2 with the final showdown featuring Glover's cop tracking the hunter to his craft. One of the most memorable scenes of the sequel has Glover discovering a Predator trophy room, which is littered with skulls both human and alien.
The most famous skull on the Predator trophy room wall belongs to the Xenomorph itself, which felt like a natural crossover since Fox owned both franchises; this easter egg eventually led to 2004's Alien Vs Predator. The human skulls belong to King Willie, the Jamaican Voodoo Posse leader who put up a fight against the hunter, and police officer Jerry Lambert (Bill Paxton). The other four trophies are alien but were seemingly created with no specific creature in mind.
There's a huge creature that resembles a T. rex but it has mandibles and four eyes. There's a skull that looks vaguely humanoid but with much larger features, and while it may not have been intended, it looks similar to H.R. Giger's Space Jockey design. Directly below this skull on the Predator trophy wall is a smaller skull that looks like another form of Predator, and the final alien creature has some vicious-looking tusks.
The Predator 2 trophy room scene would likely be loaded with more overt easter eggs had it been shot in more recent times - like including a Na'vi skull from Avatar, for instance - but this scene was pretty mindblowing to fans back in the day. The Xenomorph skull alone confirmed the series existed in the same universe as Alien while the other trophies suggested the Predator's had been hunting for a very long time.