Streptococcus constellatus is a microorganism that lives commensally in the oropharyngeal region, urogenital region, and intestinal tract. However, it can cause infection in patients with certain predisposing factors. We present a rare case of a right-sided frontal abscess caused by Streptococcus constellatus in a 47-year-old male with well-controlled type 2 diabetes mellitus patient who was injured by shrapnel pieces in the head and who was malnourished. The patient was successfully treated by surgical evacuation and antibiotherapy. Very few cases of brain abscesses caused by S. Constellatus have been reported in the literature. Only four cases in an immunocompetent patient have been reported to date.