Eutelsat 21B communications satellite, previously known as Eutelsat W6A, provides direct to home broadcasting services from geostationary orbit at a longitude of 21,5° East. The satellite replaced the Eutelsat 21A spacecraft which was launched in 1999.

Eutelsat 21B was constructed by Thales Alenia Space, and is based on the Spacebus-4000C3 satellite bus. It had a mass at launch of 5,012kgs (11,050 lb) and has a lifespan for at least 15 years. The satellite carries 40 Ku-band transponders, which are used to broadcast satellite television and radio to Europe, North Africa, Central Asia and the Middle-East.

Eutelsat 21B was originally ordered as Eutelsat W6A, as part of the W-series of satellites. In 2012, several months before its scheduled launch, W6A was renamed Eutelsat 21B. Its launch was conducted by launch operator Arianespace using an Ariane 5ECA rocket, as part of a dual launch with the Star One C3 satellite, operated by Embratel from Brazil. The launch took place from ELA-3 at Kourou, French Guiana, on 10 November 2012.