Batman is an ongoing American comic book series featuring the DC Comics superhero Batman as its main protagonist. The character, created by Bob Kane and Bill Finger, first appeared in Detective Comics #27 (cover dated May 1939). Batman proved to be so popular that a self-titled ongoing comic book series began publication with a cover date of spring 1940. It was first advertised in early April 1940, one month after the first appearance of his new sidekick, Robin the Boy Wonder. Batman comics have proven to be popular since the 1940s. Though the Batman comic book was initially launched as a quarterly publication, it later became a bimonthly series through the late 1950s, after which it became a monthly publication. In September 2011, The New 52 rebooted DC's continuity. In this new timeline, the original Batman series ended at issue #713 and was relaunched with a new first issue (cover dated November 2011). Batman (vol. 2) ran until issue #52. In 2016, DC Comics began a new relaunch of its entire line of titles called DC Rebirth, which continued continuity from the New 52. The Batman comic book was relaunched again with a new #1 issue (August 2016) and placed on a twice-monthly release schedule. The series continued through the next major relaunch by DC Comics, called Infinite Frontier, reverting to a monthly schedule with issue #106 (May 2021). Publication history The Golden Age The character of Batman made his first appearance as the lead feature of the anthology series Detective Comics #27 in May 1939. The character's popularity in Detective Comics led the publisher to launch a new title entirely dedicated to stories about Batman – a step they had only taken previously once before, with the Superman series. Batman was first published in the spring of 1940, with stories written by Bill Finger and illustrated by Bob Kane, though Finger went uncredited for years thereafter. The first issue contained three stories, each of which introduced new characters who would become notable recurring villains of Batman's rogues gallery: the Joker, Hugo Strange and Catwoman. Alfred Pennyworth, the Wayne family butler, was introduced in issue #16 (April–May 1943). Editor Whitney Ellsworth assigned a Batman story to artist Dick Sprang in 1941. Anticipating that Bob Kane would be drafted to serve in World War II, DC inventoried Sprang's work to safeguard against delays. Sprang's first published Batman work was the Batman