Apple, Samsung, and Google.
Benedict Evans has a great post describing the market for smartphones (and phones more broadly) in three charts and about 600 words. Admirable economy! Let me try to compress the argument even further.
If one looks at profits, only two companies make a substantial amount of money: Apple and Samsung. (See the chart below.)
If one looks at market share in smartphones, Google's Android platform is increasingly dominant. The Android operating system is grabbing an ever larger share of an ever larger market.