Cytoglobosins A-G (1-7), seven new cytochalasan derivatives, along with two structurally related known compounds, isochaetoglobosin D (8) and chaetoglobosin F(ex) (9), were isolated and identified from the cultures of Chaetomium globosum QEN-14, an endophytic fungus derived from the marine green alga Ulva pertusa. The structures of the new natural products as well as their relative configurations were elucidated on the basis of 1D and 2D NMR spectra (COSY, HSQC, HMBC, and NOESY) and HRESIMS data. Cytoglobosins C and D (3 and 4) displayed cytotoxic activity against the A-549 tumor cell line.