Evapotranspiration ( E T ) connects the land to the atmosphere, linking water, energy, and carbon cycles. E T is an essential climate variable with a fundamental importance, and accurate assessments of the spatiotemporal trends and variability in E T are needed from regional to continental scales. This study compared eight global actual E T datasets ( E T g l ) and the average actual E T ensemble ( E T e n s ) based on remote sensing, climate reanalysis, land-surface, and biophysical models to E T computed from basin-scale water balance ( E T w b ) in South America on monthly time scale. The 50 small-to-large basins covered major rivers and different biomes and climate types. We also examined the magnitude, seasonality, and interannual variability of E T , comparing E T g l and E T e n s with E T w b . Global E T datasets were evaluated between 2003 and 2014 from the following datasets: Breathing Earth System Simulator (BESS), ECMWF Reanalysis 5 (ERA5), Global Land Data Assimilation System (GLDAS), Global Land Evaporation Amsterdam Model (GLEAM), MOD16, Penman–Monteith–Leuning (PML), Operational Simplified Surface Energy Balance (SSEBop) and Terra Climate. By using E T w b as a basis for comparison, correlation coefficients ranged from 0.45 (SSEBop) to 0.60 ( E T e n s ), and RMSE ranged from 35.6 ( E T e n s ) to 40.5 mm·month−1 (MOD16). Overall, E T g l estimates ranged from 0 to 150 mm·month−1 in most basins in South America, while E T w b estimates showed maximum rates up to 250 mm·month−1. E T g l varied by hydroclimatic regions: (i) basins located in humid climates with low seasonality in precipitation, including the Amazon, Uruguay, and South Atlantic basins, yielded weak correlation coefficients between monthly E T g l and E T w b , and (ii) tropical and semiarid basins (areas where precipitation demonstrates a strong seasonality, as in the São Francisco, Northeast Atlantic, Paraná/Paraguay, and Tocantins basins) yielded moderate-to-strong correlation coefficients. An assessment of the interannual variability demonstrated a disagreement between E T g l and E T w b in the humid tropics (in the Amazon), with E T g l showing a wide range of interannual variability. However, in tropical, subtropical, and semiarid climates, including the Tocantins, São Francisco, Paraná, Paraguay, Uruguay, and Atlantic basins (Northeast, East, and South), we found a stronger agreement between E T g l and E T w b for interannual variability. Assessing E T datasets enables the understanding of land–atmosphere exchanges in South America, to improvement of E T estimation and monitoring for water management. [ABSTRACT FROM AUTHOR]