Captain America has sported a number of iconic costumes over the years. While not all of them have been hits (Captain America's coolest looks never appeared in any Marvel movies.
Captain America has worn a number of different variations on his classic Captain America suit in the Marvel Cinematic Universe. From his USO suit in Captain America: The First Avenger, to his stealth suit in Avengers: Infinity War. But, the coolest Cap suit that never appeared in the MCU wasn't even worn by Steve Rogers - as Bucky Barnes Captain America suit remains the coolest look to never get the big-screen treatment.
While Sam Wilson might have inherited the role of Captain America from Steve at the end of Avengers: Endgame, in the comics, Bucky took the role following The Death of Captain America arc by Ed Brubaker and Steve Epting. Captain America was assassinated by a brainwashed Sharon Carter (with Red Skulls pulling the strings), following the conclusion of the Civil War storyline. After his death, Bucky took the mantle of Captain America and wore an incredible new suit.
The new suit, designed by Alex Ross, was a bold new look that retained core elements of the original design and its evolution over the years. It remained patriotic, with the star on the chest and the stripes on his stomach. It also kept the mini eagle wings on his head, as well as his iconic shield. However, Bucky's Captain America suit featured appropriate (for Bucky) darkened arms and legs and a number of pouches for weapons (like a handgun). The suit looked different enough to tell it wasn't Steve Rogers, but similar enough to know it was Captain America. It was a pitch-perfect redesign.
Steve Rogers' Captain America wouldn't stay dead in the comics for very long, returning two years later in Brubaker, Bryant Hitch, and Butch Guice's Captain America: Reborn. While Bucky didn't stay in the role, soon returning to being the Winter Soldier, his time as Captain America will be ed as short but sweet. His suit was incredible and really made the transition from Steve to Bucky believable. Considering Falcon will be the new Captain America in the The Falcon and Winter Soldier series on Disney+, it's unlikely Bucky will ever wear the outfit in live-action - even if it's one of the best looks for Cap overall.
