Complex sentence: Welsh was a radio soap opera actress and only appeared in three films, most famously as the voice of E.T. in the 1982 film "E.T. the Extra-Terrestrial".
Split into simpler sentences: Welsh was a radio soap opera actress and only appeared in three films. She was only notably known the voice of E.T. in the 1982 film "E.T. the Extra-Terrestrial".