character of Batman to a central role in pop culture, but also (along with Watchmen) started the era known as the Dark Age of Comic Books (also known as the Modern Age and the Iron Age). The grim, seedy versions of Gotham and Batman updated the character's identity from the campy Adam West version from the 1960s Batman TV series, and proved critically and commercially successful enough that a new wave of "dark" superheroes were either created or re-popularized, and preexisting heroes were redesigned or retooled to fit this new trend. The Dark Knight Returns was one of the two comic books, alongside Watchmen, that inspired designer Vincent Connare when he created the Comic Sans font. Sequels, prequels and spin-offs A three-issue sequel written and illustrated by Miller, The Dark Knight Strikes Again, was published in 2001. A nine-issue third installment, The Dark Knight III: The Master Race, co-written by Miller and Brian Azzarello, was published approximately bi-monthly starting in late 2015. In addition, a 64-page Prestige Format one-shot co-written by Miller and Azzarello, Dark Knight Returns: The Last Crusade, which serves as a prequel to the original series, was released on June 15, 2016. Additionally, Spawn/Batman was released in 1994 as a companion to The Dark Knight Returns, and, according to Miller, the unfinished series All Star Batman & Robin, the Boy Wonder can be considered a prequel, as can the four-issue story Batman: Year One. In 1994, this version of Batman appeared in the Zero Hour: Crisis in Time crossover event playing a small role. In March 2018, he appeared in a brief cameo in the sixth and final issue of the Dark Nights: Metal event. The three-issue miniseries Superman: Year One was revealed by Frank Miller to be set in the same universe as the Dark Knight Returns series, serving as an origin story for that universe's version of Superman. Younger versions of Batman and Wonder Woman appeared in the third issue of the series, marking their first meeting with Superman. In 2019, Miller announced the name of the fourth chapter of the series, a Prestige Format one-shot entitled Dark Knight Returns: The Golden Child, released under DC Black Label. The first issue by Miller and Rafael Grampa was released December 2019. In 2018, it was announced that this version of Robin, Carrie Kelley, would be getting a spin-off in the form of a young adult graphic