Most people wouldn't put Existentialism and humor in the same sentence unless they were making some bizarre or highly ironic contrast. Those are the people who haven't read Kafka. In his most famous (though not necessarily most highly-regarded) work The Metamorphosis, Gregor Samsa wakes up transformed into a huge bug. Finding his normal range of abilities truncated—and unable to leave his room for work—he opts to fake sickness and lie in bed reflecting on his situation. Eventually his mother enters the room and the resulting mayhem is part horror, part comic farce, all philosophical investigation.
Samsa represents modern man trapped in an increasingly constricted world by inescapable mundanities and pointlessness. His situation becomes increasingly absurd as Samsa's sister eventually argues to have him killed because he is, after all, only a bug; this absurdity mirrors the devolution of society in the 20th century (particularly in the West) into hopelessness and dread. Samsa's dreadful presence in the family home also leads to their demise, until they eventually get rid of him and move on—not to a better life, but to the appearance of a better life.
Kafka's incredibly bleak assessment and indictment is fairly representative of modern Continental literature and philosophy. Man's search for meaning in a meaningless world whose traditions have been proved empty is the central theme in all his works, nowhere else portrayed quite as starkly as here. What makes his work different from his contemporaries' is the dark wit he employs. Gregor Samsa turns into a giant bug, for crying out loud. Ultimately this makes Kafka more approachable than Sartre, for example, whose work was equally despairing without the levity to make the pill a little easier to swallow. Somehow Kafka manages to infuse humor without undercutting his message. A literary masterwork and one of the finest novels of the 20th century, The Metamorphosis is necessary reading for anyone who wants to understand the intellectual climate that connected the demise of modernism and the rise of postmodernism.
The Dover edition of Metamophosis includes the unabridged text of Kafka's classic novella plus a complete study guide that helps readers gain a thorough understanding of the work's content and context.