Cause of death for Canadian actress Catherine O’Hara revealed CTV NewsCatherine O’Hara Cause of Death Revealed TMZCatherine O’Hara died of blood clot in lung, says L.A. Medical Examiner’s Office CBCCatherine O’Hara died from a pulmonary embolism. Cancer was the underlying cause Toronto StarSeth Rogen, Evan Goldberg Thank Catherine O’Hara While Accepting DGA Award The Hollywood Reporter