Characters whose job it is to Make the Lead More "normal-appearing" (e.g., Vasquez)

So in Aliens, I have read that James Cameron introduced the incredibly-badass , butchy-woman space marine Vasquez so that Ripley would, in addition to her relationship with Newt, come across as comparatively feminine.

What other characters seem to have a main purpose of “pegging the spectrum” - setting up an outlier example so that the lead appears more relate-able?

I thought of Niles on Frasier, but really the fact that they are so alike seems to be more about establishing that there is a world where this type of arrogant/dilettante mindset is considered okay…

Big Bang Theory: The presence and characters of Howard, Raj, and especially Sheldon end up making Leonard look almost normal in comparison. On most other shows Leonard would be the uber-geeky weird outlier.

Just came in to say how much I loved Vasquez:
“Hey Vasquez - anyone ever mistake you for a man?”
“No. You?”

Best line ever.

Actually, the best thing about Vasquez is how utterly the actress playing her had to transform for the role.

That pissed off Latina was played by Jenette Elise Goldstein of Beverly Hills, CA. She was awesome in the role and her others.

I was going to say “the gangsters in Boondock Saints”, but they’re also the antagonists.

But I think the foils in the Boondock Saints movies still work, because they’re all like

Wow! Revenge is FUN and COOL! And the Saints are like “no, we’re doing this because we have to, but we still have fun in other ways” But they’re still vigilantes and so would look grim and weird if not for a foil character.

Andrew Vachss’s Burke and Kinky Friedman’s Kinky Friedman are definitely more normal than their sycophants.