Complex sentence: In 1964, Mansfield turned down the role of Ginger Grant on the up-and-coming television sitcom "Gilligan's Island", although her acting roles were becoming marginalized, because the part epitomized the stereotype she wished to rid herself of.
Split into simpler sentences: In 1964, Mansfield turned down the role of Ginger Grant on the up-and-coming television sitcom "Gilligan's Island". Although her acting roles were becoming marginalized, Mansfield rejected the part as it epitomized the stereotype she wished to rid herself of.