iPhone 6s internals in the iPhone 5s body. Four inches, the A9 and a 12 MP camera, at the lowest price Apple had asked for a new iPhone.
Released March 31, 2016 · Discontinued September 12, 2018 · From $399 (16 GB, unlocked)

Apple had spent two years making iPhones bigger and a lot of people had not asked for that. The SE put the 6s internals into the iPhone 5s body: four inches, flat sides, 113 grams, the A9 and the 12-megapixel camera shooting 4K. It cost $399 unlocked, the cheapest new iPhone Apple had ever sold. There was no 3D Touch and the front camera stayed at 1.2 megapixels, which were the two places Apple found the money. Almost nothing else was missing. The reception was warm in a way Apple probably did not expect, because the constituency for a small phone turned out to be larger and considerably louder than the sales figures had suggested. Apple kept it on sale until September 2018 and quietly sold a lot of them in India and other markets where the flagship price never worked. The name came back in 2020 and again in 2022 on completely different bodies, but this is the one people mean when they talk about the small iPhone.
The SE was read as 6s internals in a 5s shell, and reviewers judged it on who it suited rather than on novelty.
Regardless of Apple's reasons for making this thing, the iPhone SE is a lovely smartphone for iOS newcomers and small-handed users alike.
But if you're looking for a first-rate smartphone that won't break the bank - or your hand - the iPhone SE deserves a spot on your shortlist.