Inclusion Criteria:

          -  Parts A, B, C, and D: 60 years of age or older

          -  Treatment-naive patients with histopathological diagnosis of classical Hodgkin
             lymphoma (Parts A, B, C, D, and E)

          -  Treatment-naive patients with CD30-expressing PTCL (Part F)

          -  Ineligible for or have declined initial conventional combination chemotherapy for HL
             (Parts A, B, C, and D)

          -  Unsuitable or unfit for initial conventional combination chemotherapy for HL (Part E)
             or CD30-expressing PTCL due to the presence of comorbidity-factors, as documented by:

               -  A CIRS score of 10 or greater

               -  Requiring assistance with or dependence on other for any instrumental activities
                  of daily living (IADLs)

          -  Measurable disease of at least 1.5 cm as documented by radiographic technique

          -  Eastern Cooperative Oncology Group (ECOG) performance status less than or equal to 3
             (Parts, A, B, C, E, and F) or less than or equal to 2 (Part D)

        Exclusion Criteria:

          -  Symptomatic neurologic disease compromising IADLs or requiring medication

          -  History of progressive multifocal leukoencephalopathy

          -  Grade 3 or higher viral, bacterial, or fungal infection within 2 weeks prior to the
             first dose of brentuximab vedotin

          -  Concurrent use of other investigational agents

          -  Chemotherapy, radiotherapy, biologics, and/or other treatment with immunotherapy not
             completed 4 weeks prior to first dose of study drug

          -  History of another malignancy within 1 year before first dose of study drug (Parts E
             and F only)

          -  Part D only:

               -  Received any prior immune-oncology therapy

               -  History of known or suspected autoimmune disease

               -  Prior allogeneic stem cell transplant

               -  History of cerebral vascular event within 6 months of first dose of study drug

               -  Active interstitial lung disease that is symptomatic or may interfere with the
                  detection or management of suspected drug-related pulmonary toxicology

               -  Known history of pancreatitis

          -  Parts D, E, and F only:

               -  Known cerebral/meningeal disease related to the underlying malignancy

               -  Systemic treatment with corticosteroids or other immunosuppressive medications
                  within 1 week of enrollment