Zsasz was the founder of an intergovernmental company and had amassed a large personal fortune. This fortune was added onto the wealth that had been given to him by his parents. At the age of 25 his parents died in a boating accident which sent him into a deep depression. As a result, Zsasz turned to gambling and ended up losing nearly all of his money in competitions around the world. One night, Zsasz had ended up in a Gotham City casino. There Zsasz gambled everything he owned and ended up losing it all to Oswald Chesterfield Cobblepot, a.k.a. the Penguin. Afterward Zsasz saw that his life was empty and felt that there was no point to his existence. Shortly after, while Zsasz attempted to commit suicide by jumping from Gotham Bridge, a homeless man tried to assault him with a knife. This homeless man assaulted him because Zsasz refused to give him money. Instinctively grabbing the knife, Zsasz realized, after searching in the man's eyes, that all life is meaningless and that nothing nor anyone matters. He then proceeded to stab the man to death as a "gift" for saving his life.
From then on, Zsasz had been reborn. He dedicated himself to "liberating" others from their pointless existence. The "zombies," as Zsasz often refers to victims as, he kills anyone children, men, and women. Zsasz has no method to his killings, this makes him very hard to track. Zsasz's preferred form of murder is slitting his victims' throats and posing them in lifelike poses. After each kill, he adds a tally mark to his body each time. He has been diagnosed as insane and is regularly incarcerated in Arkham Asylum courtesy of Batman, breaking out on occasion to carry on killing. Zsasz is said to have a special place that he is saving for Batman when he kills him. However, this "place" that he is saving is not known.
Batman: Arkham Asylum
Zsasz appears several times in Arkham Asylum. In each instance, he is holding someone hostage, and must be stopped by Batman. While his role is small, the taped conversations between him and the psychologists at the asylum are very memorable.
Batman: Arkham City
Zsasz has a smaller role in the main story of Arkham City, and is instead the heart of a series of side quests in the game. He calls Batman on payphones throughout the city, and tells Batman that if he does not answer another phone (usually clear on the other side of the city), he will kill one of his hostages. After Batman gets to each of the phones, he begins tracing the call, and each time Zsasz reveals more of his back-story. By the end Batman figures out Zsasz's location, defeats him, and frees the hostages.