Inclusion Criteria:

          -  Histologically confirmed CLL/SLL, WM, or NHL intolerant to either ≥ 2 prior standard
             of care regimens given in combination or sequentially OR have received 1 prior BTK
             inhibitor-containing regimen when a BTK inhibitor is approved as first line therapy
             (Phase 1) OR with prior treatment defined by phase 2 cohort (Phase 2 Patients only).

          -  Adequate hematologic function (Phase 1 and 1b Patients only).

          -  Responsive to transfusion support if given for thrombocytopenia or anemia (Phase 1 and
             1b Patients only).

          -  Histologically confirmed relapsed/recurrent CLL in whom venetoclax is appropriate
             standard salvage treatment; no prior venetoclax is permitted (Phase 1b Arm A Patients
             only).

          -  Histologically confirmed relapsed/refractory CLL in whom venetoclax + rituximab is
             appropriate standard salvage treatment; no prior venetoclax is permitted (Phase 1b Arm
             B Patients only).

          -  Eastern Cooperative Oncology Group (ECOG) 0-2.

          -  Adequate hepatic and renal function.

          -  Ability to receive study drug therapy orally.

          -  Willingness of men and women of reproductive potential (defined as following menarche
             and not postmenopausal [and 2 years of non-therapy-induced amenorrhea] or surgically
             sterile) to observe conventional and effective birth control.

        Exclusion Criteria:

          -  Investigational agent or anticancer therapy within 5 half-lives prior to planned start
             of specified study therapy except therapeutic monoclonal antibody treatment must be
             discontinued a minimum of 4 weeks prior to the first dose of LOXO-305. In addition, no
             concurrent systemic anticancer therapy is permitted.

          -  Major surgery within 4 weeks prior to planned start of specified study therapy.

          -  Radiotherapy with a limited field of radiation for palliation within 7 days of the
             first dose of study treatment.

          -  Pregnancy or lactation.

          -  Patients requiring therapeutic anticoagulation with warfarin.

          -  Any unresolved toxicities from prior therapy greater than CTCAE (version 5.0) Grade 2
             or greater at the time of starting study treatment except for alopecia.

          -  History of allogeneic or autologous stem cell transplant (SCT) or chimeric antigen
             receptor-modified T-cell (CAR-T) therapy within the past 60 days (180 days before the
             PK trigger) prior to planned start of specified study therapy.

          -  Known central nervous system (CNS) involvement by systemic lymphoma. Patients with
             previous treatment for CNS involvement who are neurologically stable and without
             evidence of disease may be eligible and enrolled to phase 2 Cohort 7 if a compelling
             clinical rationale is provided by the Investigator and with documented Sponsor
             approval.

          -  Active uncontrolled auto-immune cytopenia where new therapy introduced or concomitant
             therapy escalated within the 4 weeks prior to study enrollment is required to maintain
             adequate blood counts.

          -  Clinically significant, uncontrolled cardiac, cardiovascular disease or history of
             myocardial infarction within 6 months prior to planned start of LOXO-305.

          -  Active uncontrolled systemic bacterial, viral, fungal or parasitic infection.

          -  Patients who have tested positive for Human Immunodeficiency Virus (HIV) are excluded.
             For patients with unknown HIV status, HIV testing will be performed at Screening and
             result should be negative for enrollment.

          -  Clinically significant active malabsorption syndrome.

          -  Current treatment with certain strong CYP3A4 inhibitors or inducers and/or strong P-gp
             inhibitors.

          -  For patients enrolled to phase 1b Arm A or B: Patients with prior treatment with
             venetoclax or other BCL-2 inhibitors.

          -  Prior treatment with LOXO-305.

          -  Active second malignancy unless in remission and with life expectancy > 2 years.

          -  Known hypersensitivity to any component or excipient of LOXO-305.

          -  For patients enrolled to phase 1b Arm B: Patients with prior significant
             hypersensitivity, allergy, or anaphylactic reaction to rituximab/biosimilar requiring
             discontinuation.

          -  Patients with prior significant hypersensitivity to rituximab requiring
             discontinuation, prior allergic or anaphylactic reaction to rituximab (Phase 1b Arm B
             Patients only).