Martin del Bosco

For the Spanish vice-admiral in The Jew of Malta, there is unlikely to have been a direct source of inspiration.

Actually, he only comes to Malta by chance because he wants to sell some slaves at the local market. When he learns of the tribute payment to the Ottomans, he persuades the governor to withhold it and fight the Ottomans with his help instead. The promised support of the Spanish crown remains unfulfilled throughout the drama.