Though characters like Batman, Superman and Wonder Woman have become synonymous with Detective Comics at this point, when it comes to character longevity within the DC universe, none of them hold a candle to Slam Bradley, despite many casual fans likely never having heard his name. Brawling private investigator/police consultant Samuel Emerson "Slam" Bradley was introduced to the world in the very first issue of Detective Comics, way back in 1937, when he finds himself embroiled in a mystery involving the attempted theft of a socialite's prized poodle, a Chinese crime ring, and exactly as much racism and chauvinism as one could expect from a comic of the era.
Slam and his sidekick, Shorty Morgan, refer to their enemies as "Chinee," "yellow rats" and several other terms that won't be repeated on this site. After saving the day and sharing a passionate kiss with the poodle's owner, Slam dismisses her, saying he's got no time for "women trouble."
In fact, Slam's early stories proved so problematic in hindsight that there's been speculation it was the reason for the cancellation of an omnibus of Detective Comics' early issues in 2018, though DC never officially confirmed this. While Detective Comics #27 saw the introduction of Batman, who quickly became the series headliner, Slam's adventures would continue until issue 152, after which the character was phased out for decades.
But there's no keeping Slam Bradley Down, and he sees a triumphant return in Detective Comics #500, which features the PI solving the murder of a retired cop. Unfortunately, however, Shorty was lost to time. Slam would next appear in issue 572 in a celebration of the book's 50th anniversary. This story saw Bradley teaming up with Batman, Robin, Elongated Man, and... Sherlock Holmes (who's still alive in the DC Universe).
The character bounced throughout the world of DC in the following years. For a while he worked with the Metropolis Police Department, though that was later retconned to be his son, Slam Bradley Jr. Another retcon came in 2001, when Ed Brubaker wrote Slam as a lifelong Gothamite and retired from the Gotham Police Department in his arc Trail of the Catwoman. In this continuity, Bradley Jr. even fathers a child with Selena Kyle. After another retcon, readers find out that Slam was actually the lead detective on the case of the murder of Roger Elliot, father to Thomas Elliot, AKA Hush.
Slam Sr. would later pop up in Darwyn Cooke's A New Frontier (including the animated adaptation), as well as various Catwoman books. Recently, Bradley made his first live action appearance when he showed up in an episode of Batwoman, being portrayed by actor Kurt Szarka.
So the guy has come a long way and been on a lot of adventures. Die hards may well be familiar with DC's first ever detective hero, but for newcomers, the history of Slam Bradley is worth checking out. Just probably avoid the early stuff.