Last updated: May 13, 2026· By Seckin Peker

Halloween Costume Guide

Captain Carter Halloween Costume Guide

Union Jack Suit  ·  Vibranium Shield  ·  Britain’s Super Soldier

Five items, one character who took the serum first. The What If…? variant that MCU fans will recognize from across the room.

What If…? TV Series Hayley Atwell Badass Women British Military Superwoman Sword Uniform
🛡️
Quick Answer: The Captain Carter Halloween costume is five pieces built around one prop.
  • Captain Carter costume jumpsuit (essential)
  • Union Jack shield (essential)
  • Retro mid-length wig
  • Brown motorcycle boots
  • Foam sword

Peggy Carter takes the Super Soldier serum instead of Steve Rogers and spends World War II doing the job he was supposed to do, but with considerably less patience for being sidelined. In Marvel’s What If…?, voiced by Hayley Atwell, she carries a Union Jack vibranium shield and later a sword. The Union Jack suit is the costume. Without it and the shield together, you are just a woman in a bodysuit. MCU fans will place this immediately. Everyone else will need the shield to confirm it.

Items Total5 Items
DifficultyEasy
VibeWWII Super Soldier
Cost$50–$110

Captain Carter Halloween Costume Items

Captain Carter Halloween costume infographic showing all five items: Union Jack bodysuit, vibranium shield, retro wig, brown motorcycle boots, and foam sword

Captain Carter Costume Items

Affiliate links. We may earn a small commission at no extra cost to you.

Captain Carter What If…? Marvel Hayley Atwell
  • 1 Captain Carter CostumeThis is the whole costume in one piece. The Union Jack pattern on the chest and arms is what the character is built around. Get the fit right before the night — a jumpsuit that bunches at the waist or gaps at the shoulders reads as a cheap costume rather than a character choice. Order with enough time to check the fit.
    See on Amazon
  • 2 Captain Carter ShieldThe essential prop. Captain Carter’s vibranium shield carries the Union Jack design that confirms who you are to anyone who has seen the show or knows the MCU. Without it, the bodysuit alone does not do enough. Strap it to your left arm and keep it there. Do not leave it on a table.
    See on Amazon
  • 3 Retro Mid Length WigPeggy Carter’s hair is part of the 1940s period accuracy that makes the costume look intentional rather than assembled. A mid-length dark brown wig in a vintage wave style completes the silhouette. Pin it before you leave — it will shift otherwise. If your own hair is already the right length and color, you can skip this.
    See on Amazon
  • 4 Brown Motorcycle BootsMid-calf brown boots match the military-meets-superhero look of the costume. They should sit outside the suit legs, not tucked in. Check your closet first — any brown leather boot that hits mid-calf works. Nothing ankle-height and nothing with a chunky platform.
    See on Amazon
  • 5 Foam SwordCaptain Carter uses a sword alongside her shield in Season 1 of What If…?. It’s an accurate detail and gives you a prop for your right hand while the shield occupies your left. Useful at a party because it gives you something to do. Optional if you’d rather not carry two props all night.
    See on Amazon
Captain Carter cosplay showing the full Union Jack bodysuit with vibranium shield and retro wig from Marvel's What If animated series

How to Style the Captain Carter Halloween Costume

The shield is the first thing people see, and it needs to be on your arm when you walk in, not tucked under your elbow or handed to a friend. A woman in a blue and red bodysuit at a Halloween party reads as a generic superhero without it. The Union Jack shield is the detail that makes the character specific. If the suit fits well and the shield is in hand, the costume is done from the moment you enter the room.

Peggy Carter does not hesitate and does not ask for permission. She decides something and then does it. At a party, that reads as someone who walks in with purpose, holds the shield like she knows exactly what it is, and does not spend the night explaining the costume to people. When someone asks who you are, you can tell them. But you do not need to convince anyone. She never did either.

The Wig and the Strap

Pin the wig at the crown before you put the shield strap anywhere near your head. The arm strap on the shield catches on hair — synthetic or real — and pulling it off for photos will take the wig with it if it is not secured. Two pins at the crown, one at each temple. Five minutes at home saves a frustrating moment at the party.

Two Props, One Night

Carrying both the shield and the sword all night is more tiring than it sounds. The shield arm gets heavy after a few hours, and the sword ends up leaned against a wall by hour two. If you want to carry both, strap the shield loosely enough to slide off when you need a break. Or skip the sword entirely. The shield is the costume. The sword is a bonus.

Captain Carter Group Halloween Costume Ideas

The Howling Commandos, Assembled Differently

Captain Carter, Steve Rogers, Peggy Carter, Bucky Barnes, Howard Stark

This works best for a group that has all watched What If…? and Agent Carter, because the costume mix spans different shows and timelines. The visual variety is good — not everyone is in the same uniform. The one complication is that Peggy Carter and Captain Carter are technically the same person, which is either a fun detail for fans or genuinely confusing for everyone else at the party.

Captain Carter Steve Rogers Peggy Carter Bucky Barnes Howard Stark

Shield-Slingers and Patriot Queens — Across Universes

Captain Carter, Captain America, Doctor Strange, USAgent

This group is conditional. Captain America and Doctor Strange are universally recognized. USAgent is a harder costume and a smaller fanbase — most people outside MCU circles will not place him without help. If your group is all-in on Marvel and willing to build the looks correctly, the visual contrast between the Union Jack and the American flag shields is the strongest part of this concept.

Captain Carter Captain America Doctor Strange USAgent

The What If Machine — Variant Heroes Only

Captain Carter, Party Thor, Killmonger / Black Panther, Star-Lord T’Challa, Zombie Hunter Spider-Man

This is a niche concept and it will only land with people who have watched What If…? closely. At a general party, most guests will see a group of Marvel characters and not register the variant angle at all. If your group cares about the theme for its own sake, it is a fun build. If you want the concept to be understood by strangers, it will not be.

Captain Carter Party Thor Killmonger / Black Panther Star-Lord T’Challa Zombie Hunter Spider-Man
Captain Carter Halloween costume showing the Union Jack bodysuit with shield and retro mid-length wig styled for a Halloween event

Captain Carter Halloween Costume DIY Tips

What You Need to Buy vs. What You May Already Own

The costume jumpsuit and shield are the two items you need to buy specifically. The rest depends on your closet. The boots have substitutes. The wig is optional if your hair is close enough. The sword is genuinely optional.

  • Captain Carter costume: buy it, the Union Jack pattern is not something you improvise
  • Union Jack shield: buy it, this is the essential prop
  • Retro wig: buy it unless your hair is already medium-length and dark brown
  • Brown motorcycle boots: check your closet first
  • Foam sword: optional — skip it if you would rather carry one prop all night

Playing Peggy Carter at a Party

Captain Carter is not a character who performs for anyone. She is competent, direct, and occasionally impatient with people who underestimate her. That is an easy energy to hold at a party because it requires very little effort.

  • Stand straight. She does not slouch. She does not hover. She takes up the space she occupies.
  • The three quotes are short. “He does have a very punchable face.” Delivered quietly about the right person, it lands immediately.
  • When someone asks to hold the shield: you can let them. Peggy is generous with allies. Take it back after the photo.
  • She is British. A dry, unimpressed response to anything absurd is fully in character and requires no setup.
  • Skip the accent if you cannot do it convincingly. An inconsistent British accent is worse than none.

Captain Carter Halloween Costume: FAQ

Five items: a Captain Carter costume jumpsuit, a Union Jack shield, a retro mid-length wig, brown motorcycle boots, and a foam sword. The jumpsuit and shield are the two essential pieces. Without the Union Jack pattern and the shield together, the character does not read clearly at a party.

Three lines from the show that land well in a party setting:

  • “Of course… we won the war.”
  • “He does have a very punchable face.”
  • “I am not losing any friends today!”

The second one is the easiest to use in context. Pick someone, say it quietly, and move on. Peggy does not explain her opinions.

Captain Carter has a dedicated Marvel fanbase and What If…? ran through Season 3, keeping her in the conversation longer than most animated variants. She reads clearly to MCU fans. Outside that group, recognition drops off fast — a woman in a Union Jack suit could be mistaken for a generic British hero without the shield.

If your hair is already medium-length and dark brown or auburn, you can skip it. If not, the wig is worth adding. Peggy Carter’s 1940s hairstyle is part of what makes the period-accurate silhouette work alongside the Union Jack suit.

In What If…? Season 1, Captain Carter uses a sword to fight the HYDRA champion. It is an accurate detail and a useful prop because it gives you something to carry in your free hand while the shield occupies your left arm. Optional if you would rather not manage two props all night.

Yes. The natural pairing is Steve Rogers in his HYDRA Stomper armor from the show, but that build is complicated. A simpler option is Steve Rogers in his Captain America uniform, which reads immediately alongside Captain Carter. Both pairings work for anyone who knows the MCU.

Captain Carter is a variant of Peggy Carter from the Disney+ animated series What If…?, voiced by Hayley Atwell. In this timeline, Peggy takes the Super Soldier serum instead of Steve Rogers and becomes a superhero fighting HYDRA in World War II. She later joins the Guardians of the Multiverse and appears across all three seasons of the show.