Batman v Superman: Dawn of Justice, introduced Bruce Wayne, played by Ben Affleck.
After The Flash, which will have two Batmans (Michael Keaton and Ben Affleck), while in another timeline, Robert Pattinson will suit up as the Dark Knight.
Before meeting new characters and exploring other universes, the DCEU will reunite viewers with Diana in Wonder Woman 1984, where she will come face to face with businessman Maxwell Lord (Pedro Pascal) and Barbara Ann Minerva a.k.a. Cheetah (Kristen Wiig). As the title says, Wonder Woman’s second solo movie will take the audience back to 1984, which raises the question: where were the rest of the DCEU heroes in 1984?
Batman
It’s unclear when the DCEU’s Bruce Wayne was born, but based on a couple of details from Batman v Superman, such as the year when Martha and Thomas Wayne were murdered, and Bruce mentioning he was now older than his father was when he died, it's known that Bruce was in his early 40s when he made his DCEU debut. Many fans have calculated that Affleck’s Bruce Wayne was born between 1972 and 1974, meaning that during the events of Wonder Woman 1984, he’s around 10-12 years old. Martha and Thomas Wayne died in 1981, so while Diana fights against Cheetah, Bruce is still struggling with the loss of his parents and Alfred Pennyworth is doing his best to raise the young Wayne.
Superman
Kal-El/Clark Kent’s birthdate in the DCEU is listed as February 29, 1980, so he not only celebrates his birthday every four years, but he would also be only four years old in 1984. Kal-El landed on Earth on June 18, 1980, and was adopted by local farmers Jonathan and Martha Kent, who hid his true origins. Man of Steel showed that Clark’s powers began to manifest when he was 9, so during the events of Wonder Woman 1984, Clark was most likely a “normal” four-year-old kid living on a farm with his parents.
Other DCEU Heroes Alive During 1984
The rest of the already introduced DCEU heroes were born after 1984: Wonder Woman 1984 unless it jumps to the present day at some point.