The iPhone X (Roman numeral "X" pronounced "ten") is a smartphone that was developed and marketed by Apple Inc. It is part of the 11th generation of the iPhone. Available for pre-order from September 26, 2017, it was released on November 3, 2017. The naming of the iPhone X (skipping the iPhone 9 and 9s) marked the 10th anniversary of the iPhone.

The iPhone X used a glass and stainless-steel form factor and "bezel-less" design, shrinking the bezels while not having a "chin". It was the first iPhone to use an OLED screen, branded as a Super Retina HD display. It had one of the best displays and also an advanced screen for its time. The home button's fingerprint sensor was replaced with a new type of authentication called Face ID, which uses sensors to scan the user's face to unlock the device. This face-recognition capability also enabled emojis to be animated following the user's expression (Animoji). With a bezel-less design, iPhone user interaction changed significantly, using gestures to navigate the operating system rather than the home button used in all previous iPhones. At the time of its November 2017 launch, its price tag of US$999 in the United States also made it the most expensive iPhone ever, with even higher prices internationally.

Along with the iPhone 6s, iPhone 6s Plus and iPhone SE (1st generation), the iPhone X was discontinued on September 12, 2018, following the announcement of the iPhone XS, iPhone XS Max and iPhone XR devices.