Boss (Detective Conan)

Anokata, also known as Boss and That Person, is the leader of Black Organization and the overarching antagonist of Detective Conan/Case Closed franchise.

He is indirectly responsible for Shinichi's whole situation, essentially kicking off the whole story; forcing Shinichi to change his name to Conan, to move in with the Mouri family, to get in contacts with the FBI, and plunging him into various life-threatening scenarios—all in order to get his body back to normal.

In the recent chapter of manga, Anokata is revealed to be Renya Karasuma, the persumably long dead businessmen who was mentioned in File. 300, before his identity as Anokata was comfirmed in File. 1008.

"Death" and Tragedy
Renya Karasuma was the former owner of Dawn Manor, before his untimely demise (alledgly) at the age of 99, half-a-century before the start of the series, and it's around the time when the Black Organization started to take its form.

Ten years after Karasuma's presumed death, there was an auction fair held in Dawn Manor, in memory of this late man, by selling out more than 300 pieces of artifacts in his collections. In the second day of the auction fair, it was a dark and stormy night full of rain, when two soaked men visited the manor, bribing the auction fair's hosts with drugged cigarettes in order to proceed into the building. Then, they started to persuade all the guests to smoke their drugged cigarettes.

The guests all turned into a state of estacy after they smoked those cigarettes, but soon their mental state worsen, before the everyone were plundged into a state of madness. For example, one man hugged one of the artifacts and ran out of the room, screaming that he saw a devil. A woman knelt on the ground and begging for forgiveness hysterically. Another man started to prick himself with his pen. Soon, all the guests began to fight to gain the artifacts in the room, even declaring fights with blades and swords. After one night of hellish madness, the entire room was plundged into mess, leaving only 8 dead bodies and about a dozen of guests who were put into comatose.

This case soon became the only major case in Detective Conan series that, so far, has no explanation.

Trivia

 * His family name, "Karasuma", contains the word "Karasu" which means crow in Japanese. Crow is the animal motif of the Black Organization.
 * He is pratically based on James Moriarty.