Bacterial Brain Abscess: This is the most common cause of brain abscess, often resulting from the direct spread of infection from adjacent structures (e.g., otitis media, sinusitis), hematogenous spread, or following a traumatic injury to the head. The most common pathogens include Streptococcus, Staphylococcus, and Bacteroides species.

Fungal Brain Abscess: More common in immunocompromised patients, fungal abscesses can be caused by a variety of pathogens including Candida, Aspergillus, and Cryptococcus.
Parasitic Brain Abscess: Caused by parasites such as Toxoplasma gondii (especially in HIV/AIDS patients), Taenia solium (neurocysticercosis), and Acanthamoeba.
Tubercular Brain Abscess: Although less common, tuberculosis can cause brain abscesses, particularly in regions with high TB prevalence.

Subdural or Epidural Empyema: These conditions, involving infection of the spaces surrounding the brain, can present similarly to brain abscess and require urgent intervention to prevent severe complications.
Cerebral Malaria: In patients with a history of travel to endemic areas, cerebral malaria can mimic brain abscess and is critical to diagnose early due to its high mortality rate if untreated.
Herpes Simplex Encephalitis: While not an abscess, this viral infection can cause severe brain inflammation and has a high mortality rate if not promptly treated with antiviral medications.

Brain Abscess due to Nocardia: Nocardia species can cause brain abscesses, particularly in immunocompromised individuals.
Actinomycotic Brain Abscess: Rarely, Actinomyces species can cause brain abscesses, often in the context of dental procedures or oral infections.
Echinococcal (Hydatid) Brain Cyst: In endemic areas, Echinococcus granulosus can cause cystic lesions in the brain that may mimic abscesses.