This review aimed to synthesize the criteria defining marginal liver donors and to evaluate their clinical implications through an analysis of 35 studies published between 2010 and 2025, retrieved from PubMed, Scopus, Web of Science, and SciELO. The results demonstrated that donor evaluation should be multifactorial, considering criteria such as macrovesicular steatosis (acceptable up to 30%, marginal between 30–60%, and restricted above 60%), advanced donor age (>60–65 years, with age matching), hypernatremia (≥155 mEq/L, correctable), cold ischemia time (CIT >8–12 h, critical for marginal grafts), hemodynamic instability (distinguishing refractory from responsive states), metabolic comorbidities (diabetes and obesity as independent and additive risk factors), and transmissible infections (HCV and anti-HBc–positive HBV, manageable with antivirals and prophylaxis). It is concluded that the safe use of these organs depends on an integrated analysis of risks and benefits, careful recipient selection, the adoption of mitigating strategies, and the support of tools such as the Donor Risk Index (DRI) and machine perfusion technologies, consolidating this practice as a safe and necessary option to expand organ availability.