In a post on Twitter, Jeremy Conrad, who often leaks information about the cinematic superhero universe, suggested that Marvel is working on introducing the character, writing, "There's been some hinting and talk about Black Knight recently. Apparently Marvel does have a plan for him in the MCU, and they already know how he'll be introduced."
There's been some hinting and talk about Black Knight recently. Apparently Marvel does have a plan for him in the MCU, and they already know how he'll be introduced. pic.twitter.com/rOHHO9hWgU— Jeremy Conrad (@ManaByte) December 29, 2018
Although Conrad doesn't directly mention how Marvel is planning on introducing Black Knight, the image he shared seems to indicate that his introduction might have something to do with the Quantum Realm, which will likely play a major role in Avengers: Endgame.
One of the responses to Conrad's post pointed out that Black Knight's helmet has already appeared as an Easter egg in Doctor Strange.
As this is not official information from Marvel Studios, it's entirely possible that this rumor will prove untrue. Black Knight isn't a particularly big name among those unfamiliar with the comics, so it would likely take a fair amount of work to successfully incorporate the character into the MCU. Also, as Marvel Studios expects to regain the rights to the X-Men and Fantastic Four within the next six months, it seems a little odd to focus on a hero without the name recognition of those groups. Still, Marvel Studios has had success with making lesser-known heroes popular in the past, so it's possible the studio is aiming to do the same thing here.
First appearing in 1955's Black Knight #1, there have been numerous versions of the character throughout the years, and there's no indication of which version the MCU might be bringing in. The original Black Knight was Sir Percy of Scandia, who was created by Stan Lee and Joe Maneely.
If the MCU does bring the character into the fold, it's likely Marvel Studios will either use one of the supervillain versions of the character or Dane Whitman. Created by Roy Thomas and John Buscema, Whitman was the third Black Knight and has served as a member of the Avengers and several other important superhero groups.
Captain Marvel will be the next film in the MCU. Directed by Anna Boden and Ryan Fleck from a script they wrote with Liz Flahive, Carly Mensch, Meg LeFauve, Nicole Perlman and Geneva Robertson-Dworet, Captain Marvel stars Brie Larson as Carol Danvers, Samuel L. Jackson as Nick Fury, Jude Law as Starforce Commander, Clark Gregg as Phil Coulson, Lee Pace as Ronan the Accuser, Djimon Hounsou as Korath the Pursuer, Gemma Chan as Minn-Erva, Ben Mendelsohn as Talos and Lashana Lynch as Maria Rambeau. The film arrives March 8, 2019.