Even thoughDexterpremiered almost 20 years ago, the series-turned-franchise seems to be stronger than ever.

Here are the toughest adversaries that pushed the worlds most helpful serial killer to his limits.

Although the two are destined to be bitter enemies, Isaak develops a level of respect for his target.

Dexter is submerged up to his mouth in a pool of blood in a promo photo for Dexter.

Image via Showtime

Breakups are always hard, but there was never a doubt Dexter would break things off face-to-face.

A friendship with Dexter couldnt possibly last, but it was fun seeing it while it lasted.

James Doakes (Eric King).

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Keep Reading:10 Great Shows To Watch if You Love ‘Dexter’ and Its Spin-Offs

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Paul looks at Rita in Dexter.

Image via Showtime

Travis talks to Professor Gellar in front of a crucifix in Dexter.

Image via Showtime

Jordan Chase examines a vial of blood in Dexter.

Image via Showtime

Isaak Sirko, dressed in a suit, looks sternly at someone in Dexter.

Image via Showtime

Kurt Caldwell, wearing white camo, holds a gun in Dexter: New Blood.

Image via Showtime

Brian Moser stands next to a blood splatter in Dexter.

Image via Showtime

Lila West with pursed lips in Dexter.

Image via Showtime

Miguel and Dexter stand next to one another in Dexter.

Image via Showtime

Doakes glares at Dexter in a shipping yard in Dexter.

Image via Showtime

Arthur Mitchell, the Trinity Killer, looks concerned in Dexter.

Image via Showtime Networks

Michael C. Hall

Dexter: New Blood