The following health insurers offer a number of options for foreigners living in Spain.
Founded in 1954, Sanitas is the oldest health insurance company in Spain. They are partners with BUPA, the UK's leading health insurance company, so BUPA clients can transfer easily to Sanitas and vice versa. They offer many plans that are cater particularly to foreigners living in Spain.
Ibex Insurance Services Limited is an international insurance broker which was established in 2000. It is one of the largest providers of insurance to the foreign community in Spain, and has nine insurance shops in the country. They work with leading medical insurers including: AXA PPP, ALC Healthcare, DKV, Caser, BUPA, IMG Europe, Aetna, NOW and ASSSA.
Expatriate Healthcare, dedicated to providing international private health insurance for expats and travellers living and working abroad. For over a decade, Expatriate Healthcare have been underwriting, administering and providing claim services for policy holders from its City of London headquarters. Rebranded to Expatriate Group in 2015, they now have customers in 117 countries around the world, including 85 different nationalities.
This Catalan company offers several plans, from Basic through to their comprehensive Compensa Health Plan. They also have a an International Plan for frequent travellers.
Adeslas is one of Spain's biggest private insurance companies. Their website has comprehensive information for foreigners living in Spain and you can get a free online quote according to your needs.
For more about healthcare in Spain see here