Ocular infections are one of the leading causes of blindness leading to even loss of vision. Over time, several new pathogens have emerged, thus expanding the spectrum of ocular infections. Microbes tend to evade the host’s innate immunity by various mechanisms and proliferate and cause disease. The pathogenetic mechanisms remain specific to each group of microbes. Infection can be transmitted either by direct external exposure or seeded through indirect mechanisms such as hematogenous routes. Depending upon the duration of the infection, the agent can incite an acute or chronic inflammatory response. Immunodeficiency is another factor that can lead to opportunistic infections, which can rapidly spread, causing devastating systemic infections. This chapter provides an overview of the pathology of ocular bacterial, fungal, viral, and parasitic infections isolated from surgically excised specimens.