Theory of Special creation : God or super natural powers created the life.
Theory of Panspermia/Cosmozoic : Greek thinkers thought units of life called spores were transferred to different planets including earth. 'Panspermia' is still a favourite idea for some astronomers.
Theory of Spontaneous Generation : life has come from decaying matter like straw.
Louis Pasture discarded the spontaneous generation of life by using swan necked flask experiment.