The surname of Tolkien’s eldest son, who edited The Silmarillion, was Tolkien.
Christopher Tolkien was born in 1924 and became the principal editor of many of his father’s posthumously published writings. He prepared The Silmarillion for publication in 1977 by selecting, arranging, and sometimes reconciling texts that J.R.R. Tolkien had developed and revised over many years.
The question can seem deceptively simple because Christopher shared his father’s surname, but his editorial role is historically significant. He later published extensive studies of the manuscripts, including The History of Middle-earth, a twelve-volume series released between 1983 and 1996.
Christopher had a close knowledge of the fictional world. His father had read parts of the mythology to him, and Christopher also served in the Royal Air Force during the Second World War. His editorial work made a large portion of Tolkien’s unfinished legendarium available to readers.