The purpose of this study was to categorize 35 Ethiopian undergraduate physics students' alternative conceptions in the concepts of electric potential and energy. A descriptive qualitative research design was used to categorize the students' alternative conceptions. Four independently homogeneous ability focus groups were formed to elicit the students' conceptual perceptions. A five-stage thematic (categorical) framework analysis--familiarization, identifying a thematic framework, coding, charting, and interpretation--was made to analyze data of the focus group discussions. The categories of alternative conceptions were based on the students' epistemological and ontological descriptions of the concepts investigated. Consequently, the following categories were diagnosed: naive physics, lateral alternative conceptions, ontological alternative conceptions, Ohm's phenomenological primitives, mixed conceptions, and loose ideas. The extensiveness of the alternative conceptions from the epistemological and ontological perspectives was comparable and considerable. The naïve physics and lateral alternative conceptions were more extensive than the others. The alternative conceptions were less frequently and inconsistently revealed within and across the categories. In general, it was concluded that the categories have common characteristics of diversified distribution of alternative conceptions and multiple alternative conceptions of specific concepts within and across the categories. Finally, instructional and theoretical implications are forwarded.