Real Club Celta de Vigo ([reˈal ˈkluβ ˈθeltɐ ðɪ ˈβiɣʊ]; lit. 'Royal Celtic Club of Vigo'), commonly known as Celta de Vigo or simply Celta, is a Spanish professional football club based in Vigo, Galicia, that competes in La Liga, the top tier of Spanish football. Nicknamed Os Celestes (The Sky Blues), the club was founded on 1923 as Club Celta, following the merger of two Vigo-based teams. The club's home stadium is Balaídos, which seats 29,000 spectators.

The club's name is derived from the Celts, a people who once lived in the region. Its main rival is fellow Galician club Deportivo La Coruña, with whom it contests the Galician derby.

Celta have never won the league title nor Copa del Rey, although they have reached the final three times in the latter. The club finished in their best-ever position of fourth in 2002–03, qualifying for the 2003–04 UEFA Champions League, where they were eliminated by Arsenal in the round of 16. In the 2016–17 UEFA Europa League, Celta reached the semi-finals for the first time, losing to Manchester United.

R.C. Celta de Vigo was formed as a result of the ambition of Vigo's teams to achieve more at national level, where the Basque sides had been their bête noire in the Spanish Championship. The idea was to merge both teams to create a more powerful team at national level. The standard-bearer of this movement was Manuel de Castro, known as "Handicap", a sports writer for the Faro de Vigo who, from 1915, began to write in his articles about the need for a unitarian movement. The slogan of his movement was "Todo por y para Vigo" ("All for and to Vigo"), which eventually found support among the managers of Real Vigo Sporting and Real Club Fortuna de Vigo. It was backed unanimously when De Castro himself presented the motion at the assembly of the Royal Spanish Football Federation in Madrid on 22 June 1923.