So far, there has been three criminals to hold the title of Mirror Master.
Sam Scudder was already a criminal before he gained his powers. While serving time in prison for a burglary-homicide, he was working in a prison workshop, when he accidentally created a mirror that could hold an image for a certain amount of time. After this, he escaped from prison and created numerous mirror gadgets to help with his crime sprees. Calling himself the Mirror Master, Scudder terrorized Central City for years, either on his own, or as a member of the Rogue's Gallery, only to be foiled by the Flash (who was in reality, Barry Allen, the criminologist responsbile for his incarceration in the first place). Scudder was killed during the Crisis on Infinite Earths.
For a brief time, Scudder's fellow rouge Captan Boomerang held the title to commit crimes.
The current Mirror Master is a Scottish mercenary and criminal named Evan McCulloch. Originally a non-powered merc, McCulloch was given Scudder's costume and equipment by a consortium of the US government. Though he first targeted the superhero Animal Man, McCulloch eventually turned his attentions to the then current Flash, Wally West, and has been a thorn in his side since.
Powers and Abilities
Using the special mirrors he creates, Mirror Master is able to do many things. One of the various things he can do is travel to other dimensions.
In Justice League Unlimited Mirror Master appears in the episode "Flash and Substance" where he traps Flash in an old building and uses a laser disco ball to kill Flash although he is able to destroy it via shooting a record at it. He then conspires with his fellow rouges to kill Flash at his museum. They attack him Batman and Orion and in the process trap Flash and Linda Park in a mirror dimension. By the time Flash escapes the villains are defeated and Mirror Master dives into a mirror however it is shattered by Batman and he is scattered in the pieces. He later makes a cameo in the episode "The Great Brain Robbery" as part of the Legion of Doom. In this show he is voiced by Alexis Denisof.
In the show The Batman Mirror Master appears in the episode "A Mirror Darkly" where he kidnappes Gotham's richest people but is foiled by Batman, Robin, and Flash. He later appears in the episode "Lost Heroes" where Flash and Green Arrow attack him at a amusement park mirror house and is defeated when Green Arrow shoots an arrow at his mirror. Here he is voiced by John Larroquette.
He later appears in the show Batman the Brave and the Bold in the episode "Requim of the Scarlet Speedster" where he is shown in flashback hold Batman and Flash captive and tries to kill them with a laser but is defeated when Flash uses his mirror to reflect the laser. He also appears in the episode "Four Star Spectacular" where he traps Flash in a mirror maze and makes glass clones of himself. He nearly beats him however Abra Kadabra gives Flash a hint which leads him to the real one and his clones and maze shatter when he is knocked out. In this show he is voiced by Tom Kenney.