Anthony Kerrigan (1918-1991) was born in Winchester, Massachusetts, to Irish immigrant parents and spent his childhood in Cuba. In 1956 a Bollingen Foundation grant took him to Mallorca to translate Miguel de Unamuno. He stayed in the orbit of Spanish letters for years, and writers who wanted an English-language audience came to him.
He was a poet and critic, and wrote for Encyclopaedia Britannica, but his name lives on title pages as a translator. His range was wide: Unamuno, Pio Baroja, Ortega y Gasset, Camilo Jose Cela, Pablo Neruda, Borges. Much of this is argumentative, philosophical prose, and carrying it into English took an ear for tone as well as vocabulary.
His largest project was the seven-volume Selected Works of Miguel de Unamuno in the Bollingen Series from Princeton University Press, published between 1967 and 1985 and edited with Martin Nozick. He won the 1975 National Book Award in Translation for Unamuno's The Agony of Christianity and Essays on Faith, and The Tragic Sense of Life in Men and Nations was a finalist the year before.
For Borges, he edited and introduced Ficciones for Grove Press in 1962. The book was a team effort: Kerrigan translated part of it, alongside Alastair Reid, Anthony Bonner, Helen Temple and Ruthven Todd.
Start with Ficciones, ideally in the 1962 edition he shaped, introduction included. Once Borges's labyrinths and invented libraries have a hold on you, the natural next step is Unamuno's The Tragic Sense of Life, the Spanish thinker whom Borges himself admired.