If an original vampire is terrified of Silas, then it's probably not a good idea to wake Silas up. But that's exactly what the Mystic Falls group did since Silas's tomb was rumored to also house the only cure for immortality.  In retrospect, maybe they should have paid attention to Kol, the original vampire who spent the most time with witches throughout the centuries, rather than kill him.

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Silas became the big bad villain in Seasons 4 and 5 of The Vampire Diaries. But why was this first immortal truly bad? Here are the worst things he ever did.

Threatened Liz and Other Loved Ones

Liz Forbes in The Vampire Diaries

To get Bonnie to do his bidding, he goes after her friends and their families. While he can't kill Bonnie because he needs her, he can use intimidation to hurt her. Thankfully, many of Bonnie's friends are supernatural and harder to harm/kill. That's not true for their families.

Masquerading as Caroline, Silas attacked Liz, and then masqueraded as Liz when Caroline got home. Luckily, Bonnie saw through his act, and Caroline was able to save her mother. However, if more time had passed, Liz may not have survived.

Took His Frustration Out On A Happy Couple

The Vampire Diaries, Silas S 5

Hurt over his great love Amara's predicament and what he viewed as a small betrayal, now-mortal, and fully-witch, Silas is jaded about love. Sitting at a bus stop next to a couple in love, he tells them his story, ending with, "My soul is crushed." He decides to take out his anger on this random couple by first attacking the guy by starting to liquefy his internal organs. Fearing that she'll be next, the girlfriend runs away, abandoning her boyfriend.

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Fortunately, this makes Silas stop; he helps the boyfriend sit up, complains that love is fickle, and then gets the bus to go back to Mystic Falls.

Tricked Klaus Into Believing He Was Dying

Klaus thinking in The Vampire Diaries

Klaus doesn't feel that much fear about Silas. He doesn't pay heed to his brother's warnings. Since Klaus is an original vampire, nothing can really kill him except a specific white oak--of which he has safely hidden.

Silas gets in Klaus's mind, convinces Klaus that he's been stabbed with a white oak stake and that part of it remains inside of him. In extreme pain, Klaus thinks he's dying and seeks out Caroline for help. Of course, Caroline can't find anything in Klaus because nothing is there. She still digs, and later she distracts Klaus by getting in an argument with him. Klaus realizes that the white oak never was there. Caroline, in a poignant moment, states, "If Silas can make you of all people believe that you're dying, what can he do to the rest of us."

Killed Jeremy

When Silas is found by Bonnie and Jeremy, his body is stone. He clutches the cure, but they can't get it until his body becomes looser. Silas needs to be fed. Enter opportunistic Katherine who has been tracking them this whole time. Rather than give Silas a smaller portion of blood, she holds Jeremy to Silas, resulting in Jeremy being drained dry.

Although Silas didn't intentionally kill Jeremy, he did kill him. He was hungry for thousands of years, but still, he killed a central character to the Mystic Falls crew, later resulting in a key subsequent death and in Elena losing it.

Faceless And Yet Every Face

Vampire Diaries Silas Mask

It takes a while for viewers to know the true face of Silas. In his tomb, he wore a mask. Added to this, Silas is an unusual immortal. He's not really a vampire, even though he needed blood to wake up and to sustain his energy. He was a powerful witch when he was mortal, and although immortal--he still has some magic and power.

So, Silas can literally masquerade as anyone. He has worn the face of Caroline, Klaus, Liz, and more.  This is ultimate terror because the group can never feel safe. They have to constantly be on alert and worry about being manipulated.

Manipulated Bonnie Into Killing Witches

Bonnie Bennett Vampire Diaries

To gather more strength, Silas needs more sacrifices. Silas wants 12 witches. This will help with Expression Magic, a dark magic that Bonnie can harness in order to complete a spell for Silas. She thinks she can use it to get Jeremy back.

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Bonnie isn't in her right mind--being directly influenced by Silas (now wearing the mask of Shane's face). After the witches die, she wakes up and doesn't realize what happened. It could be that the witches changed her memory or it could be that Silas did. It's unclear. What's not unclear is that Silas used Bonnie.

Took Advantage of Shane's Grief

Atticus Shane in season 4 of the Vampire Diaries

Shane had lost both his child and wife, so he's in intense grief. When he first discovers Silas's tomb, he bleeds near it. Supposedly, if you bleed, you will see your dead loved one. Shane sees his wife who tells him that he can bring her and their child back to life. She gives him instructions (i.e. the sacrifices). Shane can't imagine killing people, but she assures him that he's not really killing them, that their death is temporary, and that Silas will bring them back.

His wife had been a witch when she was alive, and she had died from an over-use of Expression Magic, so maybe that's why he believed her without question. Or it could be that he believed her so easily because he was in pain. Either way, Silas took advantage of Shane's grief and got him to orchestrate heinous acts.

Hunted and Drained Katherine

Silas wanted to take the cure so that he could die a mortal death and be with Amara, whom he presumed was dead. Elena, in anger, had stuffed the cure down Katherine's throat, making Katherine mortal. Silas began to viciously hunt Katherine, who unfortunately is used to being hunted. However, this time she wasn't able to escape because she trusted Damon when he called her to come urgently. When she did, he fed her to Silas even after she begged him, "He needs all my blood. It'll kill me. Damon, please. I don't want to die."

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Silas drained Katherine (with Damon's help, of course). Katherine hung on, still, and didn't die immediately, but being drained of the cure accelerated her aging process and natural death.

Locked Stefan in a Safe to Drown

Finally, Silas reveals his true form to Stefan, and then Stefan realizes that he is part of the doppelganger legacy. Silas's true face is Stefan's. Silas reveals to Stefan that the universe had to be in balance with the immortal Silas and Amara, and thus created doppelgangers (i.e. Stefan, Elena, Katherine, etc.) that were mortal and could die throughout the 2,000 years.

Then after receiving all of this information, Silas locks Stefan in a safe where Stefan drowns, dies, and then wakes up again just to repeat the cycle for months. Had he not been found, he could have been like that for decades.

Cheated and Betrayed Qetsiyah

Qetsiyah using magic in The Vampire Diaries

Qetsiyah and Silas had both been powerful witches set to get married. Qetsiyah loved Silas and considered him her soul mate. Silas cheated on her with Amara, her handmaiden. That alone doesn't make this the worst thing that he did. What did was convincing Qetsiyah to make the immortality spell/elixir, pretending that it was for the two to use as part of their wedding rites so that they would always be together, and then taking it to use with Amara instead.

While true that Qetsiyah was crazy in love with the emphasis on crazy, Silas manipulated her by using her love for him to get him what he really wanted--an eternity with her friend, Amara.

NEXT: The Vampire Diaries Stefan's 5 Best Traits (And 5 Worst)