Akame (Akame Ga Kill!) is a deadly assassin with her skills and equally deadly Muramasa sword.
Kurome (Akame Ga Kill!) is a deadly assassin, with drugs and experiments inserted into her body and her dead-controlling sword, Yatsufusa.
Korosensei (Assassination Classroom) is a master assassin, once known as the God of Death.
Nagisa Shiota (Assasination Classroom) is a professional assassin, able to taking down a special corps soldier with years of experience in less than a second, while coming from in-front of him.
Sosuke Aizen (Bleach) assassinated all the members of Central 46.
As the Commander-in-Chief of the Onmitsukidō, Suì-Fēng (Bleach) is one of the foremost masters in the art of assassination.
Both Urahara Kisuke and Shihōin Yoruichi (Bleach) were formerly in the Onmitsukidō, as Yoruichi was the former commander in cheif, and Urahara her lieutenant, and are masterful assassins.
Haruto (Code:Breaker) is a very powerful assassin even before acquiring his powers, having a success rate of 99.9%.
Mercenary Tao (Dragon Ball) is such as skilled assassin that he can kill people using only his tongue.
The members of Trinity Raven (Fairy Tail) are the strongest of the Assassins in the Death's Head Caucus guild.
Jacob Lessio (Fairy Tail) is a genuine master of Magical Assassination, he is also one of the Spriggan 12 which makes him all the more dangerous.
Nobume Imai (Gintama) is a master swordswoman and the commander of the Mimawarigumi's assassination unit.
Mukuro, later Nobume Imai (Gintama) has been trained by Tenshoin Naraku to be an assassin even as a child, and her skills is such that she is one of the Three Wings of Naraku, and often called the "Bastard Child of the Death God".
Oboro (Gintama) the leader of the Tenshoin Naraku, considered to be the strongest assassin within group, with his mastery of Hakkei and acupuncture needles to back up his reputation.
The Zoldyck family (Hunter X Hunter) is the top assassin group in the known world.
Killua Zolodyck (Hunter X Hunter) can use techniques to assassinate.
Hatake Kakashi (Naruto) was once an assassin, working as an ANBU, and was very famous.
Momochi Zabuza (Naruto) was one of the most infamous assassins of the Kirigakure village, as his Silent Killing, especially combined with Hiding in the Mist technique, is second to none.
Hoshigaki Kisame (Naruto) was an assassin of the Kirigakure, and would kill even his own comrades to protect what he deems important.
Sai (Naruto) was an assassin for the Root organization, going as far as to eliminate emotions, and was said to be the strongest of his generation.
Nico Robin (One Piece) claimed to be an assassin before joining the Straw Hats.
Jabra (One Piece) is the third strongest assassin of CP9, though he messed up that he was required to kill more than he originally had to.
Rob Lucci (One Piece) is the strongest of the CP9, World Government's secret assassin squad, even at the tender age of 13.
Shuzen Akua (Rosario + Vampire) is the assassin of the Fairy Tales, and formerly of the Miao Family.
Golden Darkness (To Love-Ru) is a legendary intergalactic assassin.
Younger Toguro (Yu Yu Hakusho) has been hired by many as an assassin due to his fame.
Elder Toguro (Yu Yu Hakusho) is hired by many as an assassin due to his fame.