The Arrowverse has been thriving on The CW since 2012, with Arrow (2012-2020) running for eight seasons, spawning an entire universe of shows such as The Flash (2014-present), DC's Legends of Tomorrow (2016-present), Batwoman (2019-present) and most recently Superman & Lois (2021-present). The shows have introduced many characters over multiple shows. Yet, after 10 years audiences have yet to fully see DC's most famous character of all: Batman.
DC is famous for having strict rules regarding the use of the Bruce Wayne/Batman character on television, preferring to keep him for the big screen. It is for this reason that Batman has yet to make a full, in-the-flesh appearance in the Arrowverse, but that doesn't mean he doesn't exist.
On the contrary, Bruce Wayne and Batman are real characters with an incredibly rich history in the Arrowverse, being mentioned regularly and even partially appearing on Batwoman ,where he is played by Warren Christie. Through references throughout the show it is possible to piece together the history of Earth Prime's (Earth 1 before Crisis) Bruce Wayne and Batman from when he first appeared to his departure from Gotham in 2015.
Bruce Wayne's history in the Arrowverse is believed to be faithful to the comic books. We know he is the billionaire owner of Wayne Enterprises and that when he was a child his parents were murdered, resulting in him becoming Batman. This is obviously the basic origin of the character with references in Batwoman confirming this. For example, the famous pearls worn by Martha Wayne on the night she was killed play a significant role in Batwoman Season 1, Episode 4, "Who are you?," where they are stolen by Magpie, as well as serving as the entrance to the Batcave. We also know Batman fought crime in Gotham City with the assistance of Alfred Pennyworth and at least one version of Robin, and possibly more.
Whist we don't know Bruce's exact age, it is safe to assume he is similar in age to the actor that plays him, with Warren Christie being 47 years old. Therefore, Batman is likely to have existed since the late 1990s/early 2000s, making him one of the first known vigilante superheroes in the Arrowverse, along with Superman played by Tyler Hoechlin. This timeline is supported by the biggest impact Batman has had in the Arrowverse, which resulted not only in the birth of Batwoman but also her archenemy, Alice.
Kate Kane (Ruby Rose) is Bruce's cousin and in Batwoman's pilot we learn that in 2003, she was involved in a car accident that resulted in the deaths of her mother Gabi and twin sister Beth. Batman was unable to save them (only appearing in silhouette form), and Bruce always carried the guilt with him, distraught at his failure to save his aunt and cousin. Bruce's partial failure led to Beth Kane becoming the villain known as Alice.
Over the roughly 20-year career that is established, Bruce is a veteran of vigilantism, encountering many iconic foes from his rogues gallery. We learn through glimpses in Lucius Fox's journal that he encountered Ra's al Ghul and his daughter Talia al Ghul (which may have resulted in another Robin). We also know from trophies that he collected (which play a significant role in Batwoman's third season) that he also encountered Bane, Killer Croc, Penguin, Catwoman, Mr Freeze and that in 2011 he buried Poison Ivy underground. Bruce also encountered the most famous villain of them all: The Joker.
In 2015, Bruce finally snapped and, according to Luke Fox (Camrus Johnson), murdered The Joker. Whist the reason is never explicitly stated, it could possibly be the same reason that he did in Titans, as we know from Batwoman Season 3, Episode 12, "We're All Mad Here," that The Joker killed Robin. It is believed that after breaking his one rule, Bruce could no longer deal with the responsibility of being Batman, resulting in his departure and leaving Gotham in the hands of first Kate Kane and now Ryan Wilder (Javicia Leslie) as Batwoman.
Bruce may be gone, but his presence is never far away in The Arrowverse, being name-dropped regularly in Batwoman. The character has also gone on to make appearances, firstly on the front of a magazine and later when Bruce's childhood friend Tommy Elliot (Gabriel Mann) impersonated him. Though this wasn't really Bruce, it gave audiences a glimpse of what the real Bruce was possibly like. We later see Bruce when Luke Fox gets shot, and he appears as a vision in purgatory, giving us the closest thing to an Earth Prime Bruce Wayne appearance.
Will we ever see Bruce appear fully in the Arrowverse? Within Batwoman's narrative Kate (now played by Wallis Day) leaves Gotham in search of Bruce, so there is the opportunity for his return at some point in the future and with possible theories suggesting he may have ties to Ryan Wilder, his return would definitely shake things up. Or perhaps he may appear in Superman & Lois, where we could see the Arrowverse version of "The World's Finest" one day.