William Rashall Sinkin (May 19, 1913 – February 3, 2014) was an American community activist for equality, international cooperation and alternative energy in San Antonio.

While he studied at San Antonio College, he was a Phi Theta Kappa honor society charter member.

Sinkin was a precinct chairman for the Democratic Party, in San Antonio for their “two-step” primary voting process for 66 years.

The Coalition works in the areas of education, employment, health, hunger and poverty, welfare reform, immigration, issues of race, technical assistance and capacity building.

In 1976, Sinkin led a private delegation of San Antonio Jewish leaders to meet with Mexico's President Echerrveria to discuss Mexican-Jewish relations after Echeverria endorsed a United Nations General Assembly resolution that equated Zionism with racism.

The goodwill talks stressed the importance of good relations between the U.S. Jewish community and Mexico to promote economic and cultural ties.

As a lifelong advocate of alternative energy, he hosted one of San Antonio’s first major solar installations on the rooftop of his bank in the 1980s.

William R. Sinkin Eco Centro, community center for environmental sustainability at San Antonio College, was named in his honor.