These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Mammon operates as The Man Behind the Man to the devil Malebolgia. a Fallen Angel known as the lord of The Forgotten Ones, Mammon desired to create the perfect Hellspawn to assist him in ascending to rulership of all creation. To this end, Mammon haunted the bloodlines of Al Simmons and Wanda Blake, sowing death and destruction to create more Hellspawn and always leaving corpses and ruined lives in his wake. Mammon proves himself to be Spawn's greatest, most intelligent and most dangerous enemy, condemning the souls Spawn would seek to protect to hell to use them as leverage for their loved ones, and making deals to consolidate his power. When Satan returns and is furious at Mammon for claiming the throne, Mammon gets back in his former master's good graces by proposing to detonate the San Andreas Fault to kill and add the souls of many mortals to Hell's legions. After Satan is removed, Mammon unveils his master stroke- with heaven and hell sealed off from the world, Mammon sets about to conquer it from behind the scenes with Spawn's demonic daughter Morana, the product of his grand ambition.
In life, Billy Kincaid was a sadistic child killer. After being freed from jail, he lured a small girl into his ice cream truck and then murdered her. He then proceeded to chop off the girl's fingers and glue them onto a board as a trophy. After Spawn discovered Kincaid's brutal crimes, he killed Kincaid, sending him to hell. Dead, Kincaid became even worse than ever, given the task by Hell to gather more souls for them. Kincaid did this by possessing people and making them act out their worse impulses. This resulted in the murder of dozens of innocent people and the damnation of several more people to Hell, though Kincaid was having far too much fun to care. Kincaid also delighted in torturing the souls of children, especially one young boy part of the 'legion' inside of Spawn himself.
Dork Age: the period after Spawn killed Malebolgia, where he teamed up with Ab and Zab and fought vampires and british cannibals.
Big Lipped Alligator Moment: The scene with Clown wearing a cheerleading costume doing a dance number which comes out of nowhere, serves no purpose and which the protagonist doesn't even see happening. The devil himself ends the moment by dragging the clown back to hell to tell him to quit fucking around.
Special Effects Failure: The computer effects—the majority of which; mainly Violator's scenes, were done by ILM—have not aged well since its 1997 release. Spawn's cape only appears when in use (either for dramatic effect or when he's actually using it), since it was extremely difficult to animate. Plus, Malbolgia'snote Not done by ILM, but another company. mouth does not remotely follow the words he speaks, and Hell just looks like something out of a (sub-par, mind you) Pixar movie. An extremely dark Pixar movie for it to depict Hell, but still.
Conspicuous CG: Part of the problem is that the lighting always seems off nowadays, making the digital nature more obvious.
Unfortunate Implications: Spawn comes to his home to find his wife married to Terry and is lying in their yard, when Cyan comes to offer him some candy. It makes sense that they would grab their daughter and keep her away from the strange man, but its doesn't speak well of them that once they saw this man appeared to be a homeless burn victim in severe pain, their reaction was to call the cops rather than the paramedics.
Complete Monster: Clown/Violater. He's an absolute monster that torments Spawn and will pull any trick he can think of tempt him towards the path of being a demon, and he makes it clear he enjoys tormenting him and would like to see humanity suffer.
Crack Pairing: The kiss Jade shares with Spawn and subsequent implied relationship between them... really comes out of nowhere. Even when she was shown to be sympathetic towards Spawn and having doubts about her job to kill him, they only briefly met in person once before and there was never any mutual attraction implied.
Nightmare Fuel: The comic already had some scary stuff, but Violater's transformation (which depicts him as tearing through the body he has like its paper) and Creepy Monotone arguably make him more terrifying here than in the comics.
So Cool It's Awesome: The show adapts all the elements that made the comic popular and is widely regarded as a superior adaption compared to the movie.