James West is a Black American inventor and CDM profiled his career and his greatest work: co-creating the electret microphone with Gerhard Sessler at Bell Labs during an internship:
[…] the groundwork for the electret condenser, the design that would become the most ubiquitous in the world, was laid in that internship, and it started with an accident. The main issue with making a microphone compact is how to deal with power. And the breakthrough came from an experiment West was performing during that internship.
Alongside this amazing work, he has also called for greater diversity in STEM throughout his career. While at Bell Labs, he co-founded the Association of Black Laboratory Employees (ABLE), helped to create the Corporate Research Fellowship Program (CRFP) for graduate students pursuing terminal degrees in the sciences, and has mentored hundreds of students and encouraged marginalised students to pursue STEM studies and careers (source). Needless to say, James West has been an immense help to millions of people in one way or another.
(h/t to Peter Kirn for writing the CDM article!)