Slayer is a 2010 science-fiction horror film directed by Guillermo del Toro and Jason Holt, creator of the television series Hunters and Babylon 1 and also creator of the original Slayer comics. The film stars Vin Diesel, Megan Fox, John Hurt, Jet Li, Danny Glover and Ron Perlman as the leading characters, with Doug Jones playing the enigmatic antagonist Dr. Jakob Silver.
- Vin Diesel as Slayer: Diesel was first to be cast, as initially the Slayer character was moulded around his performance in the Riddick films. Diesel's character, simply called Slayer, is the only human immune to the Blood Virus, and fights alongside the survivors to find a cure. Slayer presumably dies at the end of the film, when he sacrifices himself to destroy a large amount of infected.
- Megan Fox as Grace Smith: Originally cast for Jessica Alba, del Toro and Holt decided to cast Megan Fox after her performance in Jennifer's Body. In the comics, Grace is a seductive and physically strong woman, and many of these characteristics were integrated into the film. Her intelligence, is taken from Dr. Michael Robert's assistant Kathryn, thus merging the two characters.
- John Hurt as Dr. Michael Roberts: As del Toro had worked with Hurt previously in his Hellboy films, he and Jason Holt felt that he would perform well in the film. Dr. Michael Roberts is the oldest survivor in the bunker, and is working alongside many other scientists to develop a cure. As the situation grows more dire in the film, Roberts becomes more adapted and wields a gun. He is killed during the later moments of the film, where he is massacred by an immature thyrocrax. Jack Chen, another of Slayer's comrades and close friend of Roberts, orders Slayer, Grace, and General DeSanta to leave the hive after Michael's death, destroying himself and several immature thyrocraxes in the process with a grenade.
- Jet Li as Jack Chen: Jack Chen is the wise-talking companion of Slayer, and one of the few trained soldiers. He remains close friends with his companions, and sacrifices himself to destroy the thyrocrax hive with a grenade.
- Danny Glover as General John DeSanta: Glover originally went for the role of Dr. Silver, but the film's directors felt he better suited the character of General DeSanta, who hardly appears in the comics. After a large majority of the survivor's haven is overun by infected, the General accompanies Slayer, Grace, Jack, Michael, his assistant Kathyrn, and DeSanta's two bodyguards Douglas and Mitch. After the deaths of majority of his companions, DeSanta decides to sacrifice himself to destroy a large amount of the infected. Armed with a bomb, he is about to dive below before Slayer snatches it away, sacrificing himself instead. He and Grace, along with a few dozen survivors, are the only ones to survive.
- Doug Jones as Dr. Jakob Silver Silver is percieved as the man responsible for the introduction of the Blood Virus into humanity, with the intention of recreating the human race. He is seen rarely in the film, watching the protagonists from a higher level as they proceed in their hopeless mission. General DeSanta's bodyguard, Douglas (Ron Perlman), tries to shoot him when the group sees him.
- Ron Perlman as Douglas: Douglas is General DeSanta's bodyguard, and hinted as a higher authority than his fellow bodyguard Mitch. Crude and overly angry, Douglas is quick to resort to violence and shoots anything that is not human. After taking refuge at the abandoned air bay, Roberts detects a presence in the air vents and Douglas instructs Mitch to investigate. Mitch then discovers a massive sentient heap of flesh in the centre of the air vents, before he is dragged in by one of its tentacles, presumably killed. After Mitch's death the others leave Douglas, presuming he will find his own way. As he steps out of the air bay, he is attacked by a pack of vampires, some of which he fends off before one bites and kills him, allowing the others to maul his corpse.
- Michael Hart' as Mitch: Mitch is General DeSanta's bodyguard, and a lesser to Douglas. He is told to investigate the obstruction in the air vents, where he is subsequently killed.
- Anna Rodriguez as Dr. Kathryn Andrew: Kathryn is Dr. Robert's assistant and works with him to find a cure. When the science labs are attacked, Roberts tries to help Kathryn escape, sucessfully getting her out of the labs, before she is pulled back in by a group of vampires. Her blood then splatters on the window of the lab. Kathryn is presumably turned into an infected after her death.
The film recieved generally mixed to mediocre reviews. It averages a 52% Fresh rating on Rotten Tomatoes, registering it as Rotten. The film was generally criticised for its dull story and poor perfomances. According to Rotten Tomatoes: "As always Diesel is Mr. Macho Buff Guy with no acting in Slayer, Fox was added for sex appeal, however props to Hurt, Perlman, Jones and Glover for strong performances".
SciFiLM was generally unimpressed: "Mr. Vin Diesel seems to the be the Adam Sandler/Rob Schnieder of action, and his latest offering Slayer displays the equally dull Diesel-ness. The team behind the film have formed a good script and story with the man behind the comics joining onboard, its just the acting that makes this film fall apart. Diesel is Riddick-esque as usual, Fox is just for male viewers; but John Hurt, Ron Perlman, Danny Glover, and Doug Jones render good performances that nearly save this film from the abyss. A lacking adaptation of the brilliant comic from which it is based, Slayer could have succeeded, but didn't".