There's no denying it - Zodiac signs are hella fun. There's an astrological symbol for each Justice League member as their is for every Avenger, but let's face it, nothing beats a good villain. Luckily, there's a Marvel villain for each Zodiac sign since the pantheon of evildoers in that universe is vast, varied, and vivacious. Some villains truly believe they're doing the right thing, like the progressive Aquarius Magneto, while others just revel in destruction like the Cancer that is Thanos.
A Zodiac sign is a mirror reflecting the traits that define you. Whether these Marvel villains are ruled by these traits, or have honed these attributes with an iron will, these baddies possess defining characteristics of each astrological sign. Hopefully you don't identify with any of them.
Aries don't just initiate, they take charge. They lead the charge. They are pioneers. Aries believe themselves to be preeminent. Doctor Doom adopted the name God Emperor Doom in the Secret Wars story arc when he effectively became the most powerful being in the multiverse. How's that for believing oneself to be preeminent? Doctor Doom is no backseat villain, willing to join up with a group like the Sinister Six and take orders; he believes himself to be the smartest, most capable being, and he presents that to the world.
Tauruses are most comfortable in the lap of luxury. They love opulence. They yearn for rewards and those generally come in the form of the finer things in life, including food and drink. Kingpin is nothing if not a connoisseur of good food and drink. Especially food. He's a large man - like a bull, and just as stubborn - which is of course fitting since Taurus is a bull. But another defining characteristic of Tauruses is their slow, steady, inexorable diligence in working toward the things they want. Kingpin is a plotter, whose machinations may take time to bear fruit, but that is time he's willing to wait.
Geminis are talkers who seek to probe into the mind of their conversational opponent, not unlike the silver-tongued Loki. They're fickle, mercurial, ever changing and flip-flopping, almost so unpredictable they surprise even to themselves. Loki is a trickster who has no problem taking both sides in a conflict. Geminis are quick-thinking and quick-witted, again like the barb-slinging Norse God of Mischief. The Twins are the sign of Gemini because a Gemini almost always has a counter balance, much like Loki's relationship with Thor.
Cancers can get angry. Really angry. Sometimes they let their emotions get the best of them, and that goes doubly for matters of the heart. They're passionate lovers, and when they fall, they fall hard. That sure sounds an awful lot like Thanos's relationship with Lady Death. Probably because he was scorned as a baby, discarded by his parents who didn't want a monster, Thanos loves Lady Death with a fire and fury well beyond infatuation. He loves her so much he's wiped out half the universe to prove it.