Composite pleomorphic xanthoastrocytoma (PXA)–gangliocytoma (GC) is an exceptionally rare biphasic CNS tumour, often associated with epilepsy in young adults. The case report involves a 19-year-old male presenting with a first seizure and severe headaches. Neuro-imaging showed a heterogeneous, solid-cystic lesion with calcifications and vivid contrast enhancement in the right medial temporal lobe. Slight progression on follow-up MRI led to complete surgical resection. Histopathology confirmed a composite tumour with GC features (dysmorphic neurons, NeuN+, synaptophysin+, CD34+) and PXA components (pleomorphic astrocytes, GFAP+, Rosenthal fibres, eosinophilic granular bodies, foam cells, desmoplasia). Ki-67 was <1%, and p53 expression was limited to PXA. This case underscores the diagnostic challenges of mixed glioneuronal–astrocytic tumours and the importance of multimodal evaluation, including imaging, histopathology, and molecular profiling.