Paul McCartney explained in a November 2020 piece for Rolling Stone:

‘Eleanor Rigby’ was based on old ladies I knew as a kid. For some reason or other, I got great relationships with a couple of local old ladies. I was thinking the other day, I don’t know how I met them, it wasn’t like they were family. I’d just run into them, and I’d do their shopping for them. It just felt good to me. I would sit and talk, and they’d have amazing stories. That’s what I liked. They would have stories from the wartime — because I was born actually in the war — and so these old ladies, they were participating in the war.

Paul McCartney said about the song:

I wrote “Eleanor Rigby” when I was living in London and had a piano in the basement. I used to disappear there, and while I was fiddling on a chord some words came out: “Dazzie-de-da-zu picks up the rice in the church where a wedding has been…” This idea of someone picking up rice after a wedding took it in that poignant direction, into a “lonely people” direction.

I had a bit of trouble with the name, and I’m always keen to get a name that sounds right.We were working with Eleanor Bron on [the film] Help! and I liked the name Eleanor; it was the first time I’d ever been involved with that name. I saw “Rigby” on a shop in Bristol when I was walking round the city one evening … so it became “Eleanor Rigby”.

I thought, I swear, that I made up the name Eleanor Rigby like that … But it seems that up in Woolton Cemetery, where I used to hang out a lot with John, there’s a gravestone to an Eleanor Rigby. It was either complete coincidence or in my subconscious.

At first, McCartney improvised the name “Ola Na Tungee”, which morphed into “Miss Daisy Hawkins”. He considered that “inauthentic”, so took Eleanor from Eleanor Bron, the female lead in Help!, and “Rigby” from Rigby & Evens Ltd, Wine & Spirit Shippers, a shop in Bristol.