Here are a few to get things started:
Don Henley’s The Boys of Summer as an 80s synth tune
Bossa nova version of Crowded House’s Don’t Dream It’s Over
Reggae-ish version of Aretha Franklin’s Respect
A capella men’s ensemble version of Lady Gaga’s Bad Romance
I normally go for parodies, but this would be the place to post the Devil Went Down to Georgia (Washing Machine Cover)
More seriously, 2CELLOS’ rendition of Thunderstruck is incredible: https://www.youtube.com/watch?v=uT3SBzmDxGk
They have a ton of really good ones on their channel, but that one will always be my favorite for how into it they get
That is my favorite version of Thunderstruck, even more than the original.
(There was a really cool article I read ages ago that discussed how similar metal and classical music structures are. Have no idea where I found it.)