Gastrointestinal parasites (GIPs) pose a significant threat to wildlife health and biodiversity, impacting reproductive activities, behavior, survival, and population dynamics. Identifying parasitic infections in wild animals can help to mitigate extinction risk and support conservation efforts. This study investigates the prevalence, diversity, and zoonotic risks of GIPs in six large wild mammals in Chitwan National Park, Nepal. Fresh fecal samples were collected between December 2022 and April 2023 and examined using direct wet mount and concentration methods. By analyzing 63 fecal samples: Royal Bengal Tiger () (n = 7), Asian elephant () (n = 9), One-horned rhinoceros () (n = 10), Sloth bear () (n = 9), Spotted deer () (n = 25), and Rhesus Monkey () (n = 3), we identified 19 GIP types: 3 protozoan species ( spp. and coccidia) and 16 helminth species, revealing an 85.7% infection rate. Helminths had a higher prevalence (85.7%) than protozoans (22%). Among helminths, nematodes were the most prevalent (69.8%) followed by trematodes (38.0%) and cestodes (17.4%). Eleven types of nematodes, three types of cestodes, and two types of trematodes were recorded. Multiple infections were more common than single infections. The high prevalence of GIPs indicates a major health issue that could affect species survival and conservation efforts in Chitwan National Park, highlighting the need for proactive conservation and health monitoring strategies for conservation.