All Hail the King is a 2014 American direct-to-video short film featuring the Marvel Cinematic Universe (MCU) character Trevor Slattery, produced by Marvel Studios and distributed by Walt Disney Studios Home Entertainment. It is a follow-up and spin-off of Iron Man 3 (2013), and is the fifth Marvel One-Shot short film set in the MCU, sharing continuity with the films of the franchise. The film is written and directed by Drew Pearce, and stars Ben Kingsley as Slattery, alongside Scoot McNairy, Lester Speight, and Sam Rockwell. In All Hail the King, a documentary filmmaker (McNairy) interviews the infamous fake terrorist Trevor Slattery while in jail.

Development for a One-Shot centered on Kingsley as Slattery began during production of Iron Man 3, which introduces the character. Pearce, who co-wrote that film, conceived of an idea that was contingent on Kingsley being willing to reprise his role. The actor was enthused to do so after reading the script. Filming occurred in Los Angeles over three days, with Pearce later flying to Canada to film Rockwell's appearance as Justin Hammer, reprising his role from Iron Man 2 (2010).

All Hail the King was released digitally and on the home media release of Thor: The Dark World (2013) in February 2014 and was positively received. The story of Slattery, the Mandarin, and the Ten Rings is continued in the film Shang-Chi and the Legend of the Ten Rings (2021).

Trevor Slattery, an inmate at Seagate Prison, is living with his own personal "butler" Herman, and other inmates acting as his fan club and protection. Slattery is interviewed by documentary filmmaker Jackson Norriss, who wishes to chronicle the events of the Mandarin situation. Norriss, trying to learn more about Slattery personally, recounts his past from his first casting as a child as well as his starring in the failed CBS pilot Caged Heat. Norriss eventually informs Slattery that his portrayal has angered some people, including the actual Ten Rings terrorist group, which Slattery did not know existed. Norriss tells him the history of the Mandarin and the terrorist group, before revealing that he is actually a member of the group. He then pulls out a gun and kills the guards and Herman before telling Slattery the real reason for the interview is to break him out of prison so he can meet the actual leader of the Ten Rings. Hearing this, Slattery still has no idea of the full ramifications of his posing as the Mandarin.

Additionally, Matt Gerald portrays White Power Dave; Crystal the Monkey portrays the bar monkey; and Allen Maldonado portrays Fletcher Heggs, who has a tattoo of a chess piece on his face as a nod to the comics, where he is a minor character going by "Knight".

Drew Pearce, the co-screenwriter of the Marvel Cinematic Universe (MCU) film Iron Man 3 (2013), and producer Stephen Broussard had the idea for the Marvel One-Shots short All Hail the King during the production of Iron Man 3, to provide "a fresh take" on the Mandarin character. Marvel Studios and consultant Joss Whedon were positive about the short, reliant on Ben Kingsley's involvement. Kingsley was on board after reading the script, with Pearce believing he wanted to return because he enjoyed portraying Trevor Slattery. In October 2013, Kingsley said he was working on a secret project with Marvel involving "many members of the crew that were involved in Iron Man 3". This was later revealed to be the short, written and directed by Pearce. Iron Man 3 originally had Slattery dying in the film, so the One-Shot would have been a prequel exploring part of his past life. During the editing of Iron Man 3, when it was changed to have Slattery live, Pearce was less enthused about the short being a prequel since they "inevitably lack a sense of drama" and felt continuing Slattery's journey after the events of the film was "more exciting" since "you don't know what's going to happen".

Iron Man 3 director Shane Black felt Marvel "saw so many negative things" surrounding the Mandarin's portrayal, that the short was created as "an apology to fans who were so angry". Though some of the dialogue is written in response to critics of Iron Man 3's Mandarin portrayal, the story was written simply as an extension of the Ten Rings and Mandarin storyline featured throughout the Iron Man films. Pearce wrote the short to be ambiguous enough that the storyline could be further explored in future films or television series. On the Ten Rings, Pearce stated that he found the group to be a "very powerful" part of the MCU due to their introduction in the universe's first film, and noted that producer Kevin Feige was excited to see a member of the organization be "genuinely vicious". Because of this, Pearce worked to make the action in the short "real and brutal" to juxtapose the more comedic tone leading up to it, which he felt would increase the humor of Kingsley's Slattery anyway given that the character "does not respond to anything the same way any other right minded human being" should. Speaking about adding easter eggs and nods to the comics, Pearce noted that him adding them to the script did not necessarily mean that they were a part of Marvel's bigger plan for the MCU, and said that he enjoyed "stuff[ing] it full of MCU" and waiting to see if "some of it sticks and some of it remains just a kind of charming nod". The name Caged Heat was previously used by Marvel as the working title for Iron Man 3.

All Hail the King was filmed over three days in Los Angeles, including at a "disused women's prison" in the east side of Los Angeles. Pearce believed the production was "unbelievably lucky" to align their shooting schedule with Kingsley's, who had been working on a number of different projects. Two production units were utilized in order to capture the footage for the main short and the Caged Heat material. Both Marvel and Sam Rockwell were "on board" for a cameo appearance, but Rockwell was unable to do it due to working on Poltergeist (2015). However, during post-production of that film, Rockwell read the script for the short and called Pearce, saying that he was happy to participate if his scenes could be shot in Toronto during one of his breaks. Pearce went to Canada, and filmed Rockwell on a set that was painted to match the Los Angeles shoot, saying "Rockwell came in and just nailed it".