Trying to make a noir-style Steam profile – need help!

Also, if you have suggestions for avatars, showcases, badges, achievements, or anything else to complete the aesthetic, I’d love to hear them.

That's a really cool idea. Nothing comes to mind but I'll be checking games I've played that had Noir aesthetics just in case.
Have you thought about just making your own with AI?

Arkham Knight might make the cut: https://cdn.steamstatic.com/steamcommunity/public/images/items/200260/45ad5cbb50a2fa014030de72f855036d746c0e0e.jpg

This should help ;) other keywords will expand the options I guess ;)

https://steamprofiledesign.com/

There's a few good backgrounds in the game Murdered: Soul Suspect; the one called Insignia might fit the bill, but perhaps check out the other ones, as well. The game itself might have some appropriate achievements, too.

My background could fit.

You could get a dark background, and then make an Artwork showcase to be more on theme?

Inspiration here: https://www.reddit.com/r/SteamArtworkProfiles/

Some background collations: 1 2

Appreciate all the help, detectives! 🚬🕵️‍♂️ You guys really came through with some solid suggestions. Some of these backgrounds are exactly what I was looking for. Big thanks to everyone who dropped recommendations. If I get the final look polished, I’ll make sure to share it. Cheers, and don’t get caught in the wrong alley at night. 😉

But this discussion doesn’t have to end here. If you come across more cool noir-style elements—feel free to drop them in. Not a lot of profiles follow this theme, so maybe we can help out future noir fans looking for the same vibe.