Jack the Ripper from "The Ripper" is a Serial Killer who is at first believed to be a Ripper copycat, but is soon revealed to be something far more sinister. First seen butchering numerous women, mostly hookers and strippers, throughout Milwaukee and Chicago, the Ripper cannibalized his third victim in Chicago, carving out her kidneys to eat. Sending taunting letters of his crimes to the press, the Ripper arranges a meeting with a young reporter while claiming he won't kill anyone the night they would meet, however he kills her anyway. After escaping police custody and brutalizing many officers and innocents who try to restrain him, the Ripper is revealed to be the actual Jack the Ripper, having spent the past decades traveling the world and always murdering 5 women in each location he terrorizes, having killed over 70 women over the years. Jack the Ripper was a mysterious figure whose crimes were never given justification beyond sheer sadism and hatred.
Robert Palmer from "The Devil's Platform" is a senator obsessed with gaining as much personal power as possible, and to this end, made a deal with the Prince of Darkness for supernatural abilities. Using these abilities, of which he pays for by regularly sacrificing animals and "higher forms of life", Palmer kills off all of his political opponents, with their wives and friends being casualties as well. When Palmer's campaign manager plans to reveal his crimes to the public, Palmer sends the elevator his manager is on plummeting to the ground, killing him and the numerous other innocents onboard. A secretary, aware of Palmer's part in the elevator crash, tries to blackmail him into paying her to keep quiet about it, and Palmer responds by trying to maul her in his hellhound form; when she survives and is sent to the hospital, Palmer pursues and kills her in her weakened state. After murdering another of his opponents in a car crash, Palmer tries to manipulate Carl Kolchak into signing his soul over to Palmer, and wastes no time in trying to butcher Kolchak when he refuses. Smug and power hungry, Robert Palmer stood out even to Kolchak as one of the most wicked villains he ever faced.
Helen of Troy from "The Youth Killer" has the longest Historical Rapsheet in the series. A beautiful demigoddess who made a deal with the powerful goddess Hecate for eternal life, Helen is required to drain the life out of physically perfect individuals on a regular basis to retain her youth, a process that inevitably kills her victims, something she takes pleasure from. Having lived for hundreds of years, Helen uses a computer dating service in the present to find victims, and drains the life out of three of them throughout the episode, nearly getting Kolchak killed when he tries to interfere. Defined by her callousness and lust for beauty, Helen of Troy was the most beautiful, and most self-centered, foe Kolchak ever faced.
Critical Research Failure: Quite a lot in the Rakshasa episode. The most egregious error being the beef curry (which is the worst possible sacrilege for a religion in which cows are sacred). Other glaring errors pertain to the Rakshasas and the mythology behind them. Furthermore, the Swastikas drawn are actually the slanted Nazi variant, the vast majority of Hindu swastikas being straight.
At the same time, it is correctly noted that the Swastika is a Hindu symbol and a symbol of good, and several Rakshasas in Hindu mythology are known for cannibalism and magical disguises.
Cult Classic: A textbook case. It faltered in its day, but the humor and supernatural stories attracted a niche audience that guaranteed the show a long life in reruns and tie-in novels.
"Funny Aneurysm" Moment: In "The Zombie" (the show's second episode), Vincenzo tries to butter up Kolchak, who sees it as a ploy to stick him with an unwanted assignment. Kolchak lists some of the other times this happened (such as having to rewrite a co-worker's piece), capping off by saying this usually ends with him getting stuck with all the work and frustration. That ended up being a complaint of Darren McGavin; not only was he the star and featured in most scenes, but he purportedly did a lot of extra work writing and producing the show without proper credit.
Harsher in Hindsight: Not long after The Night Strangler came out, Ted Bundy started preying on young women in Seattle.
Playing Against Type: Phil Silvers in "Horror in the Heights"; John "Piglet" Fiedler as fast-talking morgue attendant Gordon "Gordie the Ghoul" Spangler; Jim Backus as a motorcycle dealer; Jamie Farr as a high school science teacher in "Primal Scream."
Special Effects Failure: In "Bad Medicine" there are a couple times where they try to show a dog that's been savaged to death by the evil metamorph. They're ruined a little by how the dead dogs move.