In the manga,like her anime counterpart, Beryl was an Earth sorceress who hated the people of the Moon
as she had an unrequited love for Prince Endymion and hated Princess Serenity for being his lover. She was granted powers by the evil entity Queen Metalia, who had descended to Earth from the Sun when it detected the malice in Beryl's heart, hoping to use her to obtain the Silver Crystal and conquer Earth. With these powers granted by Metalia, Beryl managed to turn Endymion's subjects, including the Shitennou, against him.
The most significant difference between the anime and manga was the manner in which Queen Beryl was defeated in the past. Rather than being sealed away by Queen Serenity when Metalia killed the Sailor Senshi, Princess, and Prince, she herself was the one who killed Prince Endymion after he rejected her. Beryl killed him as he was protecting Serenity, in front of the Princess' eyes; seeing this left her so distraught that she took her own life in response. When Sailor Venus saw this she slew Beryl with the Holy Blade, but it was too late to win the battle.
When Queen Serenity unleashed the power of the Silver Crystal against Metalia, she was so upset that she was unable to seal the entity completely away. This allowed the evil entity to reawaken Beryl and her underlings as her servants in the next life. Beryl was reincarnated as a normal woman who, while in the Arctic Circle, discovered the ruins of the Dark Kingdom at D Point and there reawakened Metalia. Metalia returned Beryl's memories, then helped her to reawaken the Shitennou. They began to gather energy for Metalia and Beryl sent out her underlings to search for the Silver Crystal, in hopes that she could become the Queen of Earth with Prince Endymion at her side.
Beryl has immense magical power, but she uses most of it to channel the life energy harvested by her servants to the entity called Queen Metalia. In most versions of the story, she has the ability to corrupt others into serving the powers of darkness.