Though he was the first head of this Cabinet-level agency, Ruckelshaus is perhaps better known for his role in a Nixon-era government standoff. During the infamous "Saturday Night Massacre," Attorney General Elliot Richardson and Ruckelshaus, an assistant AG at the time, refused to fire Watergate special prosecutor Archibald Cox despite President Nixon's adamant request. He was no pushover at the EPA either. Ruckelshaus helped build the organization in its formative years, forcing highly polluted cities and automobile companies to meet code and banning the general use of the pesticide DDT.