Inclusion Criteria:

          -  Histologically or cytologically documented locally advanced or metastatic solid tumors
             meeting the following study drug-specific criteria:

          -  Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1

          -  Life expectancy greater than or equal to (>/=) 12 weeks

          -  Measurable disease, as defined by RECIST v1.1

          -  Adequate hematologic and end organ function as confirmed by laboratory results within
             14 days prior to the first study treatment

        Inclusion criteria specific to Arm A: Atezolizumab+ Ipilimumab

          -  Escalation stage: NSCLC participants

          -  Mandatory biopsy cohort: NSCLC or melanoma atezolizumab

          -  Prior atezolizumab-treated cohort: participants with NSCLC or melanoma previously
             treated with atezolizumab

        Inclusion criteria specific to Arm B: Atezolizumab+ Interferon alfa-2b

          -  Escalation stage: RCC or melanoma participants

          -  Expansion stage: RCC or melanoma participants

          -  Mandatory biopsy cohort: RCC or melanoma participants

          -  Prior immunotherapy-treated cohort: participants with RCC, NSCLC, or melanoma
             previously treated with programmed death-ligand 1 (PD-L1)/ Programmed death 1 (PD-1)

        Inclusion Criteria Specific to Arm C (Atezolizumab plus PEG-Interferon Alafa-2a):

        - Cohort 1: participants with RCC

        Inclusion Criteria Specific to Arm D (Atezolizumab plus PEG-Interferon Alfa-2a
        +Bevacizumab)

          -  Cohort 1: participants with metastatic RCC with no prior line of systemic therapy for
             metastatic disease

          -  Cohorts 2-3: disease progression during or after at least one previous systemic,
             anti-cancer treatment for locally advanced or metastatic non-squamous solid tumors;
             participants with sensitizing epidermal growth factor receptor (EGFR) mutations or
             anaplastic lymphoma kinase (ALK) rearrangements must have failed or are intolerant to
             prior treatment with EGFR or ALK inhibitors; participants with melanoma with
             actionable BRAF mutations (e.g., V600) must have failed or are intolerant to prior
             treatment with BRAF inhibitors

        Inclusion Criteria Specific to Arm E (Atezolizumab +Obinutuzumab)

        - R/M HNSCC participants with at least one prior line of systemic therapy

        Inclusion Criteria Specific to prior Anti-PD-L1/PD-1 Treated Cohorts:

          -  No permanent discontinuation of atezolizumab or other immunotherapies due to a
             treatment-related adverse event

          -  Recovery from all immunotherapy-related adverse events to Grade less than or equal to
             (≤) 1 or baseline at the time of consent

        Exclusion Criteria:

        General Medical Exclusions:

          -  Pregnant and lactating women

          -  Any approved anti-cancer therapy, including chemotherapy or hormonal therapy, within 3
             weeks prior to initiation of study treatment, with the following exception: (1)
             hormone-replacement therapy or oral contraceptives; (2) tyrosine kinase inhibitors
             (TKIs) that have been discontinued greater than (>) 7 days prior to Cycle 1, Day 1,
             baseline scans must be obtained after discontinuation of prior TKIs

          -  Investigational therapy within 28 days prior to initiation of study treatment

          -  History of severe allergic, anaphylactic, or other hypersensitivity reactions to
             chimeric or humanized antibodies or fusion proteins

          -  Known hypersensitivity or allergy to Chinese hamster ovary cell products or any
             component of the atezolizumab formulation

          -  History of or active autoimmune disease

          -  History of idiopathic pulmonary fibrosis (including pneumonitis), drug-induced
             pneumonitis, organizing pneumonia, risk of pulmonary toxicity, or evidence of active
             pneumonitis on screening chest computed tomography (CT) scan

          -  Prior allogeneic bone marrow transplantation or prior solid organ transplantation

          -  History of human immunodeficiency virus (HIV)

          -  Participants with active hepatitis B

          -  Participants with active hepatitis C

          -  Participants with active tuberculosis

          -  Participants with a history of confirmed progressive multifocal leukoencephalopathy

          -  Any serious medical condition, physical examination finding, or abnormality in
             clinical laboratory tests that, in the investigator's judgment, precludes the
             participant's safe participation in and completion of the study

        Cancer-Specific Exclusions:

          -  Active or untreated central nervous system (CNS) metastases, as determined by CT or
             magnetic resonance imaging (MRI) evaluation during screening and prior radiographic
             assessments

          -  Spinal cord compression not definitively treated with surgery and/or radiation or
             previously diagnosed and treated spinal cord compression without evidence that disease
             has been clinically stable for >/= 2 weeks prior to screening

          -  Leptomeningeal disease

          -  Uncontrolled pleural effusion, pericardial effusion, or ascites requiring recurrent
             drainage procedures (once monthly or more frequently); participants with indwelling
             catheters are allowed.

          -  Uncontrolled tumor-related pain

          -  Uncontrolled hypercalcemia or symptomatic hypercalcemia requiring continued use of
             bisphosphonate therapy or denosumab

          -  History of other malignancy within 2 years prior to screening, except for
             appropriately treated carcinoma in situ of the cervix, non-melanoma skin carcinoma,
             Stage I uterine cancer, localized prostate cancer treated with curative intent, ductal
             carcinoma in situ treated surgically with curative intent, or other cancers with a
             similar outcome

        Exclusion Criteria Related to Medications:

          -  Prior treatment with cluster of differentiation 137 (CD137) agonists or immune
             checkpoint blockade therapies (Note: Participants enrolled in the prior
             anti-PD-L1/PD-1 treated cohorts with melanoma may have received prior anti-cytotoxic
             T-lymphocyte-associated protein 4 treatment or other immunotherapies)

          -  Treatment with systemic immunostimulatory agents within four weeks or five half-lives
             of the drug, whichever is shorter, prior to Cycle 1, Day 1

          -  Treatment with systemic immunosuppressive medications within 2 weeks prior to Cycle 1,
             Day 1 (the use of inhaled corticosteroids and mineralocorticoids is allowed)

        Exclusion Criteria Specific to Interferon Alpha Therapy (Arms B-D):

          -  History of depression, suicidal ideation or behavior, bipolar disorder, or psychosis

          -  Hypersensitivity to interferon alpha or any component of the product

        Exclusion Criteria Specific to Bevacizumab (Arm D)

          -  Inadequately controlled hypertension

          -  Prior history of hypertensive crisis or hypertensive encephalopathy

          -  Significant vascular disease within 6 months prior to Day 1

          -  History of hemoptysis

          -  Evidence of bleeding diathesis or significant coagulopathy (in the absence of
             therapeutic anticoagulation)

          -  History of tracheoesophageal fistula, gastrointestinal perforation, or intra-abdominal
             abscess within 6 months prior to Day 1

          -  Clinical signs or symptoms of gastrointestinal obstruction or requirement for routine
             parenteral hydration, parenteral nutrition, or tube feeding

          -  Evidence of abdominal free air that is not explained by paracentesis or recent
             surgical procedure

          -  Proteinuria, as demonstrated by urine dipstick or > 1.0 gram of protein in a 24-hour
             urine collection

          -  Metastatic disease that involves major airways or blood vessels, or centrally located
             mediastinal tumor masses of large volume

        Exclusion Criteria Specific Obinutuzumab (Arm E)

          -  Hypersensitivity to obinutuzumab

          -  Prior treatment with obinutuzumab