A consistently entertaining trope is the "dark magical girl." This is a female character who's often a dark reflection of the hero or heroine. Unfortunate circumstances mold her from both, and she leads an incredibly lonely life as a result. She then takes that loneliness out on the world, usually finding solace in a greater evil.
Several dark magical girls pepper the gaming landscape. Their backstories and personalities may differ in specifics, but they all ultimately fall into the same trope. More importantly, they nearly always create a memorably chaotic experience.
7 Trilla - Star Wars: Jedi Fallen Order
The Sith are dark perversions of Jedi. Thus, many Sith characters in Star Wars serve as sinister parallels of the heroes. That's the case with Jedi Fallen Order's villain, Trilla. Though low on the Dark Side hierarchy, she still pursues the protagonists with dogged determination. That stems from her unwilling profession. She was once a Jedi apprentice to Cere Junda herself, but the Empire captured and tortured her into becoming a loyal thrall. Now, she serves Darth Vader as an Inquisitor: hunting down fugitive Force users throughout the galaxy.
This mission pits her against Cal Kestis, the Jedi currently guided by Junda. It's an ideal dynamic to place doubts in his head, and it creates an affecting contrast as the depths of her damage become clear. It's not as developed as it could be, but it successfully raises the stakes by showcasing the enemy's twisted methods from a personal perspective.
6 Lumina - Lightning Returns: Final Fantasy 13
Lightning's foe in the third Final Fantasy 13 title is Lumina. The mysterious trickster resembles Serah, the heroine's naive sister who took center stage in the second entry. In reality, though, Lumina is a counterpoint to Lightning herself. She's a manifestation of the warrior's feelings and vulnerabilities. This renders the heroine emotionless, at least more than she already was.
It also makes Lumina the best character in the game by default. Lightning is such a black hole of emotion by design that she puts players to sleep. Lumina's unpredictable nature is a breath of fresh air. What's more is that her aforementioned resemblance to Lightning's sister creates an intriguing psychological game, one which the villainess immensely enjoys playing. However, considering how much of her character hinges on that dynamic, her journey would be more compelling if her rival had a pulse.
5 Veronica - The Fire Emblem Series
Here's a character who fits the trope to a tee. Introduced in Fire Emblem Heroes, Veronica is a literal magician girl. What's more is that she's a malicious princess: a title usually associated with naïveté and altruism. That said, neither of these aspects has the weight of the trope's greatest aspect.
Veronica opposes the Order of Heroes and the Kingdom of Askr out of spite. She resents the opposing realm's joyful and prosperous nature, which is why she lashes out. Jealousy as motivation could paint the character one of two ways: tragically engaging or just plain petty. Luckily, Veronica falls into the former category, standing as a formidable foe whom Fire Emblem fans won't soon forget.
4 Mustache Girl - A Hat In Time
Hat Kid may look like a child, but her responsible use of her tech shows maturity beyond her years. She understands the power of her equipment and how putting it toward selfish gains could irreparably damage the universe.
Mustache Girl has no such inhibitions. She's content to put the tech toward self-gratification, and she has no problem stepping on others to achieve her goals. This alienates her from Hat Kid and all others. That isolation fuels her anger, causing her to inflict more damage. It's a vicious cycle, one which plays out organically. In the end, despite its bright and friendly aesthetic, A Hat in Time sports one of the more tragic gaming villains of recent years.
3 Harley Quinn - The Batman: Arkham Series
Though not a direct reflection of Batman, Harley was still morphed by unfortunate circumstances. She was once a successful psychologist, but she felt lonely and constrained. As a result, she fell in love with her patient, the Joker, who encouraged her to cut loose and manipulated her into becoming his henchwoman.
The scenario is a double-edged sword. On one hand, it means Harley is extremely entertaining throughout the Arkham games. On the other, a tragically abusive subtext runs through it. Quinn always tries to please the Joker, yet he constantly keeps her under his thumb. However, it's that poignant desperation--mixed with sheer chaotic energy--which keeps both her and the fans coming back.
2 Android 21 - Dragon Ball FighterZ
Created in the vein of Majin Buu, this feminine android mirrors the pink menace in many ways. One example comes when she splits into two versions. One aids the Dragon Ball heroes as a mild-mannered scientist while the other causes untold chaos with an army of clones and an insatiable appetite. She craves the company of others, but not because she's lonely. She just wants to eat them.
That's what makes Android 21 so much fun. Her childlike attitude creates such a hilarious contrast with her sinister scheming. As a result, she chews (pun intended) every bit of scenery in spectacular fashion. These instances help the android emerge as the best Dragon Ball game villain.
1 Alice - The Shin Megami Tensei Series
This demonic child was based on Alice in Wonderland. She obviously lacks the purity of that heroine, and, thus, much of her dialogue is a twisted rendition of what one would expect from an innocent child. Rather than asking for a lollipop, she politely requests that her enemies die horribly. To complement this, her magic mainly deals with death.
This morbid move set makes Alice a mainstay of Shin Megami Tensei. Unfortunately, fans don't see anything beneath her haunting exterior. They get hints of her origin as the ghost of a dead girl, but she ultimately amounts to little more than an enemy to fight or a Personato summon. Still, that minimal implication mixes well with her creepy characteristics to leave a foreboding impact. Sometimes, less is more.