Summary
The longest variant of the Boeing 787 Dreamliner, with the greatest capacity, is the -10.
Launched in 2013 following a commitment by Singapore Airlines to order the type, the 787-10 first flew on 8 June 2017.
By late 2017 the type had firm orders for over 170 aircraft, with airlines keen to use it as a replacement for older Boeing 777-200 and Airbus A330-300 aircraft. It was also seen as a competitor for the Airbus A350, or simply has a higher capacity variant for airlines which already had 787 fleets.
To date there have been around 100 Boeing 787-10 aircraft delivered, with more still on order.
Which Airlines Fly the 787-10?
These are the carriers currently operating the Boeing 787-10:
All Nippon Airways, Japan

Photo (c) Masakatsu Ukon
British Airways, UK

British Airways 787-10
Etihad Airways, UAE
EVA Air, Taiwan
KLM, Netherlands

Adam Moreira (AEMoreira042281), CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
Korean Air
Saudia, Saudi Arabia
Singapore Airlines, Singapore

Singapore 787-10. Photo © Boeing Airplanes
United Airlines, USA

MarcelX42, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
Vietnam Airlines, Vietnam
Future operators of the 787-10 will include:
- Air Canada
- Air New Zealand
- China Airlines
- Emirates
- Qantas
Title Image: Bidgee, CC BY-SA 3.0 AU <https://creativecommons.org/licenses/by-sa/3.0/au/deed.en>, via Wikimedia Commons