Ella Fitzgerald and Louis Armstrong recorded a couple of classic albums together. They're a treasure to hear, though I have to admit I'm not as huge a fan of them as I am of their work individually. Though both jazz singers who perform scat, I just don't think their voices mesh ideally, at least to my taste, though there is certainly a richness there.
That said, I was browsing YouTube last night and by total chance -- I swear I wasn't even looking for anything by Ella Fitzgerald -- I came upon a video I couldn't not post. I had no idea that Ella Fitzgerald even recorded this song; I've never seen it on any album of hers. It might be on one, I've just never seen it. But here it is on video.
This is Ella Fitzgerald in Helsinki, Finland, singing..."Hello, Dolly!":