Killer es o fue un grupo de cuatro integrantes, siendo la vocalista Siiri Nordin el miembro más popular de la banda.Forman o alguna vez formaron parte de Dynasty, una asociación de bandas finlandesas a la que también pertenecen Kwan, The Rasmus, Mariko y Von Hertzen Brothers.

Actualmente se encuentran en un estado de ruptura indeterminada.
Sin embargo su sencillo debut Hurrican fue lanzado en febrero de 2001. En agosto del mismo año lanzaron; All I Want, la cual se convirtió en un éxito en Finlandia. Más tarde, también en 2001, lanzaron su primer álbum Sickeningly Pretty & Unpleasantly Vain.

En el sencillo Fire se incluye la colaboración que tuvo Lauri Ylonen (vocalista de The Rasmus) en la canción All I want, la cual canto con Siiri una vez en el Ankkarock.

En 2003, lanzaron la continuación de su álbum debut, llamada Sure You Know How To Drive This Thing. Este álbum incluye la canción Naughty Boy, la cual fue un gran hit y se convirtió en una de las cancionas más tocadas en la radio durante el verano en Finlandia; también alcanzó el #1 en la lista de éxitos de MTV Up North.

En febrero de 2005, Timo Huthala, el bajista del grupo, anunció en el sitio web oficial de la banda que se separarían por un tiempo indeterminado.

"Esto no incluyó ningún gran drama, solo cosas normales. En primer lugar, trabajamos durante cinco años sin un descanso decente, así que estamos agotados de ideas y energía. Y en segundo lugar tenemos distintas ideas sobre el rumbo que Killer debe seguir musicalmente. Desde que no pudimos coincidir en nuestras ideas en esto tampoco pudimos continuar"

It was in the darkest night I remember. I walked alone, lost, I did not remember in what city I was or how I had gotten there. Something caught my attention in an alley, isolated, in the gloom. It was a gravestone. Without understanding what a grave was doing there alone I approached and sat down in front. Terrified, I was able to read that my name was inscribed in it ... with my date of birth ... and with the date in which we were.

At that moment, like an apparition, I could see that behind me was a man, blond hair, long, dressed in white, holding an electric guitar case with one hand and a bottle of Jack Daniel's with the other. "Good evening, I'm Paul White, are you okay?" I was confused ... "I just discovered that I died." He, undeterred, offered me the Jack Daniel's bottle and asked: "And will you let that detail stop you?" Not knowing what to answer, I took a long drink, cleared my throat, and then noticed a figure in the same alley, a humanoid figure, like marble. "But ... what the hell ..." Paul White sat next to me. "He's an old friend, known as Sir Beljerick," I could see him smile as he added, "Let's wake him up." He took the guitar and, with a frenetic, wild rhythm, began to scratch his strings, singing melodies of fury and disagreement, of passion and nocturnality.

It had not been just a few minutes when a car, at full speed, stopped skidding just before us. From there 2 individuals got down, armed with an electric bass and a battery respectively. The one who called himself Pibi, placed himself on the drums, began to beat his instrument as if it were holding onto his life, with the despair of those who can lose everything, except music. His partner, Mario, addressed me. "I was resting on a cruise ship, in a Jacuzzi with a drink in my hand. But I heard you and I had to come. " For a moment I wanted to ask how he could have heard us, how he had been able to get there so quickly ... but it soon passed. I did not want to understand anything, not anymore. Mario grabbed the strings of the bass and joined what was already a party, or a coven. Moving his fingers between the frets I seemed to hear wolves making love to the corpse of their last prey.

They all looked at Sir Beljerick ... and, somehow, his statue opened its eyes, and began to move. It came alive. He approached us while I, riding between the bars of music, was barely aware of the night, of the city, of life or death. With voice of torment without surrender, of a thousand hells overcome, Sir Beljerick, he sang, pointing out: "Get up and let's make the revolution".