Inclusion Criteria:
* Subject has a solid tumor of a type likely or known to either overexpress wild-type Epidermal Growth Factor Receptor (EGFR) or to express variant III mutant EGFR (e.g., head and neck squamous cell carcinoma, Non-small Cell Lung Carcinoma (NSCLC), and colorectal carcinoma).
* Subject must have disease that is not amenable to surgical resection or other approved therapeutic options with curative intent.
* Subject cannot tolerate or must not be eligible for other approved therapeutic options with known survival advantage.
* Subject has an Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 to 2.
* Subject must have measurable disease as defined by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 with at least 1 extrahepatic 2 cm lesion.
Exclusion Criteria:
* Subject has received anticancer therapy including chemotherapy, immunotherapy, radiotherapy, hormonal, biologic, or any investigational therapy within a period of 14 days prior to the first dose of ABT-806i.
* Subject has received a prior EGFR-directed monoclonal antibody within a period of 4 weeks prior to the first dose of ABT-806i.
* Subject has unresolved clinically significant toxicities from prior anticancer therapy, defined as any Common Terminology Criteria for Adverse Events (CTCAE) Grade 2 or higher.
* Subject has had major surgery within 21 days prior to the first dose of ABT-806i.
* Subject has a clinically significant uncontrolled condition(s) including but not limited to the following:
* Active uncontrolled infection
* Symptomatic congestive heart failure
* Unstable angina pectoris or cardiac arrhythmia
* Psychiatric illness/social situation that would limit compliance with the study requirements
