Santiago's breakthrough role was in the highly successful NBC's drama series HEROES. He also starred opposite Benicio del Toro in CHE, for which he received critical acclaim for his portrayal Cuban guerrilla commander Camilo Cienfuegos.

Other recent highlights include MERLIN, THE MUSKETEERS, TRANSFORMERS & BIG LITTLE LIES. He also recently narrated the successful BBC documentary series PATAGONIA.

He is currently filming for the second series of SALVATION for CBS.