Kevin Conroy is confirmed to be appearing in the Arrowverse's highly-anticipated Crisis on Infinite Earths crossover, but why is he only playing Bruce Wayne and not Batman? The seminal comic book storyline, upon which the five-hour event is based, was originally published in 1985. Designed to help commemorate DC's 50th anniversary, the 12-issue series ultimately changed the entire landscape of the DC universe, killing off multiple characters and merging various parallel Earths into one. As such, it is fondly remembered as one of the greatest comic book stories to this day. The ambitious adaptation was confirmed back in December.

Crisis on Infinite Earths will see the heroes of Arrow team up with those of The Flash, Supergirl, Legends of Tomorrow, and even Batwoman. As teased in each show's season finale, the superhero collective will unite to combat the multiverse-destroying threat of The Anti-Monitor. Along the way, the characters will encounter a whole host of new and familiar faces. Brandon Routh will play one of each - appearing as both Ray Palmer and Kingdom Come Supermanwhile Conroy will guest-star as Bruce Wayne.

Related: What Kevin Conroy Could Look Like As Bruce Wayne In The Arrowverse

The announcement provoked a wave of excitement. After all, having debuted as the character all the way back in 1992 and voiced him consistently to this day, Conroy is technically the longest-serving Batman of all time. Despite strictly appearing in animation or video games, he is also regularly considered the best by fans. As such, it was considered well overdue for Conroy to appear in live-action. The announcement, however, also led to the inevitable question - why was he cast as Bruce Wayne but not Batman?

Arrowverse Heroes During Crisis on Earth-X. Arrow The Flash Legends of Tomorrow Supergirl

The most obvious answer would probably be age. Conroy is 63 years old, so jumping around and attacking from the shadows would likely fall outside of his considerable abilities. On the other hand, that's nothing a stunt double couldn't fix, enabling the show to have even a much older Bruce Wayne still able to hold his own. The more probable answer is that the Arrowverse is still not allowed to use Batman. There was a time even mentions of Gotham city and Bruce Wayne were off-limits. Warner Bros. has since eased back on that decision, however. Still, an actual appearance of the Caped Crusader is clearly a different matter altogether - especially with a Robert Pattinson-starring film in the works.

It also makes sense from a story point-of-view, given what was previously established in this combined universe. Elseworlds previously revealed that Batman had disappeared from Gotham. That mystery looks set to continue hanging over Batwoman's proceedings and will likely go unanswered for some time - if ever. Thus allowing Kate Kane's taking up of the mantle to not be overshadowed. Then again, Conroy's appearance solely as Bruce could solidify that the reason he permanently left the cape and cowl behind is that a worth successor had already taken over in his absence.

It was also revealed that Conroy's Bruce Wayne would be one from the future. As such, Crisis on Infinite Earths will most likely reveal that he has long since retired. It's currently unknown whether he ventures into the past or if the present-day heroes travel to him. Either way, it's a shrewd move on the part of the writers, simultaneously avoiding the appearance of Batman in a narrative sense and tapping into the era of the hero's legacy largely unexplored on-screen. As such, though fans will remain disappointed not to see Conroy officially suit up, the potential for references and easter eggs (perhaps even to Batman Beyond and Terry McGinnis) will surely offer some compensation.

More: Kingdom Come Superman Explained: How Brandon Routh's New Version Is Different

Crisis on Infinite Earths will begin on The CW on December 8.