This week, former commissioner of Gotham City, Jim Gordon, takes up the role of Batman. It's an unexpected but wildly fascinating choice, especially since Gordon gets to use a ten-foot-tall suit of advanced armor.
So who else has stood-in as Batman when Bruce Wayne was unavailable? Several people, as a matter of fact.
We know all about the Batmen from alternate realities, but we're looking here purely at the continuity of the main DC Universe. (Sorry, Thomas Wayne.)
Hey, nobody can be available 24/7/365. When Bruce needs a break — or he's, you know, dead — Gotham still needs a Batman.
Here we present the others who've worn the Batsuit, replacing Bruce Wayne when it was necessary.
Conditioned since childhood to become the next avatar for the Sacred Order of Saint Dumas, Valley began his career as a vigilante with a passion for brutality. When he crossed paths with Batman, he saw the error of his ways and put his formidable skills to work as a member of Batman's team. A short time later, Batman's back was broken by Bane in the Knightfall storyline, and for more than a year, Valley served as Batman in Bruce's stead, though his mental conditioning caused him to become unstable and increasingly violent. He wore a high-tech suit of armor that he designed himself.
After Bruce's back was healed, Valley stepped down. He became a new crime-fighter called Azrael and sought penance for his misdeads while operating as Batman.
The original Robin grew up and became the acrobatic superhero Nightwing. This protégé of the Bat has worn the Batsuit several times over the years. His first (and rather brief) fill-in gig took place after Jean-Paul Valley was forced to relinquish the mantle when he became too dangerous. Many years later, Grayson became Batman for an extended period during and after Grant Morrison's Battle for the Cowl storyline.
Second Robin Jason Todd died at the hands of the Joker, was later resurrected and went on a vengeance-fueled crime spree as the Red Hood. When Batman seemingly died, Todd fashioned his own Batsuit for Battle of the Cowl and declared himself Batman. He was taken down by Dick Grayson, and eventually returned to the light side of the Force.
Yet another entrant in Battle for the Cowl, young Tim Drake by this time had grown big enough to wear a Batsuit while Bruce Wayne was believed dead. Drake was never a true contender to take over for Bruce, but his combination of skilled deductive reasoning and fighting skills made him an effective one.
More recently, Tim was transported to a future version of Gotham, where he was given the futuristic Batsuit formerly worn by Terry McGinnis (see below). He's currently the Batman of Neo-Gotham in the pages of Batman Beyond.
In a possible future depicted in Batman #666, Damian Wayne grew up and took on the role of Batman in his father's stead. Bruce was murdered in front of him, while Damian was still a young boy working as Robin, so adult Damian was propelled by grief. But he was never his father — and had no problem utilizing his no-compromise worldview to bring criminals to justice.
In the future city of Neo-Gotham, a young man named Terry McGinnis was mentored by an older Bruce Wayne to take up the mantle of Batman. This incarnation was based on the popular animated TV series Batman Beyond, but DC didn't induct Terry McGinnis into its official canon until many years later. His Batsuit was like nothing ever seen before, capable of technological feats far more advanced than anything possible today.
That's right, a villain actually replaced Batman. And on more than one occasion.
A few times over the years, Hugo Strange has used his obsession with Batman as fuel to try and become Batman himself. He's even appeared in public as Batman. To do this, Strange — who was originally conceived of as Batman's version of Moriarty, by the way — has used various means to take Bruce Wayne out of the picture so that he could move in. These replacement attempts, while sometimes successful, were always short-lived.
Despite this, Strange still knows Batman's true identity is Bruce Wayne, but his demented state of mind has prevented anyone from believing him.