Max Mercury is the name of a superhero in the DC Comics universe. He is based on the hero Quicksilver, who first appeared in Quality Comics' National Comics #5; however, since almost nothing was revealed about that character, save that he possessed super-speed and his secret identity had the first name "Max", writer Mark Waid was free to reinvent the character in The Flash, without contradicting anything. When the character reappeared in early 1990s issues of The Flash, his name had to be changed from "Quicksilver" to "Mercury" to avoid confusion with Marvel Comics' Quicksilver.
In Waid's origin of the character, he was originally a scout with the US Cavalry in the 1860's. A friend of the local Indian tribes, he was shocked and dismayed to find them massacred by the command of his commanding officer. Enchanted by a dying Indian shaman, he gained superspeed. In the years that followed, he became known to the Indians as 'Ahwehota' ('He Who Runs Beyond The Wind'), and to everyone else as WindRunner.
Mercury has repeatedly travelled through time, seeking to enter the so-called Speed Force. He usually bounces off and finds himself decades in the future. His first attempt left him in the 1890's, where he created a new identity for himself as Whip Whirlwind. Later, he travelled ahead again, and was active in the 1930's and 40's as Quicksilver.
In 1948, he had an affair with the wife of a doctor who had saved his life. When the doctor learned of this, Max fled into the future once more, reappearing in the early 1960's where he battled Savitar and was bounced still further forward in time.
In recent years, he has been the mentor of first Wally West (the third Flash) and later Bart Allen (Impulse, later Kid Flash III). While living with Impulse, Max learned that his earlier affair had resulted in a child, a daughter named Helen Clairborne. At the current time, Max is missing in action, apparently posessed by the spirit of Golden Age supervillain The Rival.
