The Holy Grail has many legends: some say that it was used in the Last Supper, some say it was used to gather Christ's blood after he was pierced by Spear of Destiny, Some legends say it was both. Holy Grail is connected to King Arthur as well, as he and his Knights of the Round Table sought it in the ultimate quest.
Later in life the Grail was given name San Greal to give it more of medieval feeling and it in turn created the word play of Sang Real (blood line).
The first Lady Pendragon - Guinevere, was prophesied to bore a lineage of great warrior women. One problem with it was the she was sterile. She then returned from Avalon, to again seek the Holy Grail, as she hoped it would make her fertile again. At first she was imprison by the church fathers in Vatican, as she had turned her back on her people and religion. At the day when she was about to be executed, her friend and ally Sir Percival saved her with the cost of his own life. Guinevere used magic to hide her looks and went back to Vatican to find the Holy Grail. This time she succeeded, and not only did it restore her ability to bore children, but she got pregnant from drinking from it.
When the three Talismans ( Garnet Orb, Deep Aqua Mirror, and Space Sword) were combined, they formed the Holy Grail, which allowed Sailor Moon to transform into Super Sailor Moon.
Holy Grail was rumored to be an artifact that grants power to whomever drinks from it.
A girl named Faith witness how her father interrogates Templars of the location of Holy Grail. Seeing a dark side of her father she plans to stop him at all costs. She knows that if her father drinks from that grail, he will become immortal and then there can be no peace, so she joins her father's army in disguise. She rushes to the grail and battles her own father. Not able to defeat him, she drinks from that grail herself. But the Templars had put a curse on the Grail, and Faith lost her soul. Faith then kills her father and renames herself; Lady Death. She was cursed to search and kill for her soul for eternity.
The Grail used in Last Supper was hunted by many, but never found. Even the real one was eventually believed to be a fake. There was a scroll from a cult of vampires connected to the Holy Grail. At the present time Baroness Blood had learned from the scroll that the Holy Grail can free a vampire form all the weaknesses, even blood thirst; but only when one drinks from it at Christmas. She sent one of her new recruits, Kenneth Crichton to retrieve the chalice from London's Museum of National History; he was successful. Baroness Blood drank from the cup at the dawn, and crushed the Grail after she was done with it. It is also possible that the Holy Grail allowed her to have children again; as nine months later, her and Kenneth Crichton's son was born.
It was the Third Crusade, when Christians invaded Jerusalem. Kenneth Irons managed to find the Holy Grail and he drank from there along with Gerard Irons (his son), Sir Renaud de Gaudin and one unnamed man; each of them received eternal life. Renaud however was disfigured as his faith was not pure; to him the eternal life was a curse.
The Holy Grail is made out of regular stone, but it is infused with spiritual powers. Batman was given the Holy Grail to safeguard it. He was chosen for the task mainly because his ancestor was one of the Knights of Round Table and sought it in his time. Batman decided not to use it and only safeguard it. He first tested of its originality by pouring water from it to his bullet wound; the bullet wound healed and the bullet in it disappeared. Ra's Al Ghul has sought it for centuries, and failed each time, he learned that the Holy Grail is located in Gotham and he again started a quest to get it. Azrael had found out that Batman has the Grail, but he made no effort to obtain it, he only came to warn Batman that if he knows then others know, and there will be many who will stop at nothing to get their hands on the Holy Grail. Penguin and Catwoman are one of those who had learned that a priceless artifact has arrived in Gotham, Penguin knows it's location and hires Catwoman to steal it from Batman. Catwoman failed that task as her burglary was interrupted by Ra's Al Ghul's men. In the end Talia Al Ghul convinced her father to drop the hunt for the Holy Grail. Batman realized that he is not able to safeguard the Grail for long and gave it to Superman.
Future: Year 3000
In the year 3000 the new generation of King Arthur and the Knights of the Round Table were seeking the Grail, to save their friend, Sir Tom. They headed for Glastonbury Tor, where the Grail was rumored to be. Sir Percival was the one who solved the puzzle to obtain the Grail, by choosing a simple cube instead of crucifix. He then unfolded the cube into a cross and it transformed into the Holy Grail. Then he immediately used it to cure Sir Tom. After that Percival transformed into more human look and ascended himself. Sir Lancelot was chosen as a new guardian of the Holy Grail. But Lancelot failed and Morgana and Mordred got the Holy Grail.
Since the DC wide reboot into the new 52, it has been revealed that one of the goals of the loosely assembled team known as the Demon Knights, is to locate and protect the Grail.