Stimuli that have been frequently used to induce self-relevant processing are highly familiar to individuals (e.g., self-name [SN] and self-face). One's surname is an important form of collective self-concept; it represents the line of ancestry, and is psychologically salient. According to this concept, a stranger with the same surname elicits salient self-relevant processing, despite unfamiliarity; however, this has not yet been directly investigated. The present study adopted a three-stimulus oddball paradigm and multimodal electroencephalography to study the potential self-relevant processing of such stimuli. Behavioral results indicated that same surname unfamiliar (SSU) names were rated more self-relevant than different surname unfamiliar (DSU) names, although they were rated equally unfamiliar to subjects. Analysis of event-related potential showed similar P2 enhancement in response to SN and SSU when compared to DSU. In contrast, the self-relevant effect on P3 amplitudes and theta synchronization decreased linearly from SN, SSU, to DSU conditions. Thus, both the behavioral and electrophysiological data indicate that unfamiliar names with the same surname evoke reliable self-relevant processing.