Eight new diterpenoid acids, namely, talascortenes A-G (1-7) and 5α,9β-dihydroxyisocupressic acid (8), with four different carbon skeletons, were isolated and identified from the endozoic fungal strain Talaromyces scorteus AS-242 that was obtained from the inner fresh tissue of a deep sea Cerianthus sp. sea anemone. The structures of the new compounds were elucidated by detailed interpretation of NMR and mass spectrometric data. X-ray crystallographic analysis of compounds 1-5 and 7 confirmed their structures and absolute configurations. Compounds 1-8 showed inhibitory activities against several human, aquatic, and plant pathogens with MIC values ranging from 1 to 32 μg/mL.