Javi Gracia was most recently the manager of Watford FC.
The experienced 47-year-old signed an 18-month contact with the Hornets having previously coached clubs in his native Spain as well as Greece and Russia.
During two seasons with Málaga he achieved back-to-back top-10 La Liga finishes, famously defeating eventual Champions League and Spanish champions Barcelona at the Camp Nou in February 2015.
The following campaign his Málaga side went unbeaten against both Real Madrid and Atlético Madrid on their way to an impressive eighth-place 2015/16 finish.
Having started his senior coaching career in 2007 with Segunda División B outfit Pontevedra, Gracia secured promotion to the Spanish second-tier with Cádiz before spells in Greece with Olympiakos Volou and Kerkyra.
In 2012/13 he once again masterminded a promotion campaign, this time returning Almería to the Spanish top-flight before stints with Osasuna and Russian Premier League club Rubin Kazan either side of his Málaga stay.