Answer:
Franz Kafka was a a writer of German-speaking language, from Bohemia, who lived between 1883 and 1924. He is considered one of the greatest writers of the 20th century and most of his works are known today.
In answer to the question: Which main theme is present in many of Franz Kafka´s works, there is not one single theme that can be said to appear in all of them, as he tended to write about a lot of issues that concerned the human mind, but there are some that have been repetitive in most of his works: alienation, existential anxiety, probably being one of the most common ones, guilt and absurdity. There is also a recurrence on criticism for bureacracy, and other such themes, but the ones mentioned above, are among the most common both in his stories and in his novels.