HBO is the latest entertainment company to suffer a major data breach, as episodes of upcoming television shows were leaked online.

According to Entertainment Weekly, hackers claim to have stolen 1.5 terabytes of data from the prestige TV network, and leaked the scripts for Ballers and Room 104.

The hackers promised more script leaks, possibly including an upcoming episode of HBO's ratings behemoth Game of Thrones.

An anonymous email was sent Sunday to reporters announcing the hack.

"Hi to all mankind. The greatest leak of cyber space era is happening. What's its name? Oh I forget to tell. Its HBO and Game of Thrones……!!!!!!" it read.

HBO spokesperson Jeff Cusson would not tell The Associated Press which specific TV episodes, movies or other video the hackers made off with.

"HBO recently experienced a cyber incident, which resulted in the compromise of proprietary information," the network said in a statement.

"We immediately began investigating the incident and are working with law enforcement and outside cybersecurity firms. Data protection is a top priority at HBO, and we take seriously our responsibility to protect the data we hold."

In an email sent to company staff, HBO chair and CEO Richard Plepler wrote: "As most of you have probably heard by now, there has been a cyber incident directed at the company which has resulted in some stolen proprietary information, including some of our programming. Any intrusion of this nature is obviously disruptive, unsettling, and disturbing for all of us."

Hacking history

HBO has been sensitive to potential hacks that threaten to spoil the plots of upcoming shows, especially the massively popular Game of Thrones, which counts shocking moments of betrayal among its highest selling points.

In 2015, four episodes of the show's fifth season were leaked online, supposedly from advance screener copies sent to press. HBO has refrained from sending episodes in advance to press ever since. 

In May, hackers demanded a large ransom to be paid in bitcoin after they claimed to have stolen a copy of Pirates of the Caribbean: Dead Men Tell No Tales from Disney.

And another hacker group, known as The Dark Overlord, released copies of the latest season of Netflix's Orange is the New Black after the network refused to pay a ransom.

They all pale in comparison to the 2014 hack of Sony Pictures emails, with stolen files totalling approximately 100 terabytes of data and, among other things, leading to a minor political row between the U.S. and North Korea thanks to Seth Rogen's comedy The Interview.

With files from The Associated Press