Hans's cousin and a fellow patient at the sanatorium, whose disciplined and dutiful nature contrasts with the sanatorium's leisurely atmosphere. He serves as a stabilizing force for Hans due to their shared background.

A charismatic and enigmatic patient at the sanatorium who captivates Hans, symbolizing both allure and independence. Her frequent departures and returns highlight her complex relationship with the sanatorium environment.

An Italian humanist and a patient at the sanatorium who becomes one of Hans's intellectual mentors. His literary and cultural critiques provide insight into various philosophical and political ideas.

A Jesuit intellectual whose radical ideas and debates with Settembrini challenge Hans's perspectives. He represents a counterpoint to Settembrini's liberal views with his own more extreme ideologies.

A charismatic and wealthy Dutchman whose larger-than-life presence at the sanatorium adds to the narrative's exploration of ideas and sensation. Peeperkorn's interactions emphasize the themes of passion and sensory experience.