Artur Mas -President of the Generalitat de Catalunya (as of August 2014):

 Mariano Rajoy -Prime Minister of Spain (as of August 2014)

Catalonia (same for Valencian Community and Balearic Islands) boasts a rich and varied political life filled with excitement and controversy over major issues of local, national, and international importance. (Wikipedia entry)

With a Catalan self-determination referendum (CataloniaVotes) (9 November 2014) and a further de facto independence referendum via early election (25 September 2015), the political future of Catalonia is uncertain but with room from exciting proposals from all sides of the political spectrum.

Generalitat de Catalunya --The official government of Catalonia (currently autonomous community of Catalonia in Spain) (How is the Generalitat organized?) 

Parlament de Catalunya -Parliament of Catalonia

Generalitat Valenciana -The official government of the Valencian Community

Govern de les Illes Balears -The official government of the Balearic Islands

Public Diplomacy Council of Catalonia

Estatut d'Autonomia --Statute of Autonomy. Passed in 2006

Convergència i Unió (Convergence and Union) Catalan nationalist alliance (Democratic Convergence of Catalonia plus Democratic Union of Catalonia). Conservative/centrist.

Esquerra Republicana de Catalunya (Republican Left of Catalonia) Catalan independentist. Left wing.

Partit dels Socialistes de Catalunya (Socialists' Party of Catalonia) Catalan referent of the Spanish Socialist Workers' Party (PSOE). Social-democratic.

Iniciativa per Catalunya Verds (Initiative for Catalonia Greens) Ecosocialist.

Partit Popular de Catalunya --Catalonia branch of the Spanish Partido Popular

Ciutadans -Partido de la Ciudadanía

Assemblea Nacional Catalana --An organization that promotes the independence of Catalonia through democratic and peaceful means

Catalan National Assembly --English website of the Assemblea Nacional Catalana

Associacio Ciutadans de Catalunya -- Organization promoted by a group of Catalan intellectuals opposed to Catalan nationalism

Manuel Valls (Prime Minister of France as of August 2014) is Catalan (born in Barcelona 1962 from Catalan father and Swiss mother)

Let Catalans Vote  

Referendum Catalonia