Thermo Fisher Scientific Inc. (NYSE: TMO), the world leader in serving science, today announced that Peter M. Wilver, senior vice president and chief financial officer, has decided to retire, effective March 31, 2016. The company's board of directors has elected Stephen Williamson, currently vice president of financial operations, as his successor, effective August 1, 2015. Williamson will report to Marc N. Casper, president and chief executive officer of Thermo Fisher.