Third window syndromes refer to a diverse group of disorders characterized by abnormal bony openings in the otic capsule, disrupting the normal mechanics of inner ear fluid dynamics. These syndromes can lead to both auditory and vestibular symptoms, such as conductive hearing loss, autophony, and sound- or pressure-induced vertigo. While superior semicircular canal dehiscence (SSCD) is the most well-known, this chapter focuses on less common variants, including enlarged vestibular aqueduct syndrome (EVAS), posterior and lateral canal dehiscence, cochlear dehiscences, and anomalies like Incomplete Partition Type III. Diagnostic tools, particularly CT imaging and vestibular-evoked myogenic potentials (VEMP), are essential for evaluation. A unifying classification scheme—otic capsule dehiscence (OCD)—is introduced to encompass the full spectrum of third window lesions. Management varies depending on etiology, symptoms, and associated pathology, ranging from conservative observation to complex surgical repair.