A Study to Assess the Safety and Tolerability of Atezolizumab in Combination With Other Immune-Modulating Therapies in Participants With Locally Advanced or Metastatic Solid Tumors

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