It is a common joke that Warner Bros. will put Batman in almost any show. One of the most popular ones was Spawn/Batman from Frank Miller and Todd MacFarlane, which was a pair of 1994 one-shots. The two are coming back together to do it again because of the popularity of the series.
DC put out an animated trailer to hype up the one-shot of Batman/Spawn, which will be released in December. The story begins when the Court of Owls call on Spawn to do what they cannot and kill Batman. It probably won't work out in the Owls' favor even though it doesn't seem to be in the same continuity as the previous ones.
Spawn has appeared in a number of games before, with the most recent being his appearance in the latest game from the company. Spawn was a guest character in Soul Calibur II back in 2002 and the image character appeared in Ready Player One. He might show up in the video game once his movie is released.
The movie will be released on December 13. Spawn and Batman will be included in a Collected Edition bundle on November 15 if the trailer has you reminiscing.
Do you want to know more about io9. House of the Dragon and Lord of the Rings: The Rings of Power, as well as what's next for the DC Universe on film and TV, can be found on this page.