Terretonin O (1), a new meroterpenoid, was isolated individually from both methanolic extracts of thermophilic Aspergillus terreus TM8 and marine Aspergillus terreus LGO13. The recently reported terretonins M (2) and N (3) were further isolated from the fungus LGO13 along with nine known compounds, terrelumamide A (4), terrein (5), methyl-3,4,5-trimethoxyl-2-[2-(nicotinamide)benzamido]benzoate (6), butyrolactones I-III (7-9), aspulvinone O (10), ergosterol, ergost-4-ene-3-one and methyl linoleate. Structure of terretonin O (1) was established on the bases of HRESIMS, 1D and 2D NMR spectra and comparison with its analogues in literatures. The relative stereochemistry of 1 was assigned on the basis of NOESY spectra and comparison with reported configuration of its congener compounds 2 and 3. The antimicrobial and cytotoxic activities of the fungal extracts and obtained compounds were assayed using a set of microorganisms, and cervix carcinoma cell line (KB-3-1), respectively. Isolation and taxonomical characterization of the producing strains are reported.