Final answer:
Henrik Ibsen is the playwright known for exploring realistic characters and modern struggles, particularly highlighted in his play 'A Doll's House', which challenges societal norms and institutions.
Step-by-step explanation:
The playwright who explores realistic characters experiencing modern struggles and the tragic consequences of placing faith in institutions is Henrik Ibsen. As the father of modern realistic drama, Ibsen's influence on theater was profound; his plays eschewed soliloquy in favor of direct expressions of psychological motivation and were concerned with the social issues of his day, such as the role of women, venereal diseases, and the stranglehold of societal norms. His most controversial work, A Doll's House, exemplified the modern tragedy, with its protagonist Nora Helmer making the shocking decision to leave her family in pursuit of personal freedom and truth, proposing that true tragedy can reside in everyday domestic situations.