Donald Robert Nelson–known to family and friends as Don, Dad, and Papa–peacefully passed into eternity on Tuesday, August 4, 2026, in New Haven, Connecticut, after living courageously with Parkinson's disease.

Don was born on May 12, 1940, in Indianapolis, Indiana, to the Reverend William Nelson and Lotta Nelson, and grew up in Akron, Ohio. At North High School, he was elected student government president and received the school’s highest student honor in 1958–early recognition of the charisma, character, and leadership that would distinguish him throughout his life.

As a student at the University of Wisconsin–Madison, Don's leadership and commitment to service deepened. He was elected to the Student Senate and served as chairman of the District III Commission, campaigning on a platform that called for “more effective admissions policy, tangible student economic benefits, improved student counseling and services, and more student involvement in educational affairs.” Long before international student travel became commonplace, he championed international exchange programs and affordable opportunities for students to build meaningful relationships across cultures, reflecting a lifelong belief that understanding begins with genuine human connection.

After graduating in 1963 with a Bachelor of Arts in Political Science, Don joined the United States Navy as a pilot. He attained the rank of lieutenant during his four years of service that took him around the world, including an assignment on the French Riviera, where he lived with his first wife, Linda, and where his first son, David, was born in Nice, France. Two years later, while Don was stationed near Boston, their second son Mark was born at Chelsea Naval Hospital in Massachusetts.

Following his military service, Don earned a master’s degree in Policy Sciences from the State University of New York at Buffalo, where he also pursued doctoral studies in the same field, completing all required coursework and beginning his dissertation. He went on to a career devoted to helping people realize their potential, expanding opportunities for others, and strengthening organizations. As the Director of Education at Yale University’s Drug Dependence Institute from 1973 to 1978, he built innovative drug and alcohol education and treatment programs throughout New England in partnership with Yale’s Department of Psychiatry and the U.S. Department of Health, Education, and Welfare. He later directed the Alcohol Services Organization in New Haven (1978 to 1982), establishing treatment and prevention programs across South Central Connecticut, and served on the State of Connecticut Drug and Alcohol Council. During this period, Don also taught Organizational Development and Group Dynamics in the graduate program at Antioch College in Keene, New Hampshire.

On January 11, 1975, Don married Sandra Mae Nelson, the love of his life. They welcomed their daughter Risë, and built a partnership that would span 51 years—a union his son once described, without hesitation, as the best decision his father ever made.

In 1982, Don joined Pfizer, where he created drug and alcohol prevention programs across its Research and Manufacturing Divisions. That work marked the beginning of an extraordinary 22-year career in human resources and executive leadership. In 1993, at the direct request of Pfizer’s CEO, Don led succession planning for the company’s senior leadership, developing individualized plans to prepare the next generation of leaders.

His ability to recognize talent, cultivate potential, and combine strategic insight with genuine care led to increasingly consequential assignments. Don served as Senior Vice President of Human Resources for Pfizer Europe from 1995 to 1998 and for Pfizer Global Research from 1998 to 2000. Don’s career reached its capstone in 2000, when he was named Senior Executive Vice President of Human Resources for Pfizer's Worldwide Pharmaceuticals Group, a position he held until his retirement in 2004. During his tenure, he led Pfizer's Human Resources integration for the company's landmark $116 billion acquisition of Warner-Lambert, one of the largest mergers in corporate history. He later served on the Corporate Leadership Team overseeing Pfizer's acquisition of Pharmacia. Colleagues remember him as the architect of Pfizer's senior leadership development capability, a role ideally suited to a man who genuinely believed in–and cared about–the potential of others and invested in helping them realize it.

After retiring from Pfizer in 2004, Don continued to mentor and develop leaders. From 2004 to 2008, he consulted for Johnson & Johnson’s Women of Color Leadership Program, helping open doors for a new generation of corporate leaders.

For all of Don's professional accomplishments, those who knew him rarely spoke first about his achievements or titles. They remembered how he made them feel. He had a rare gift for making people feel seen, valued, and important. With genuine warmth, curiosity, and respect, he listened intently, remembered people’s names, and left them feeling that they truly mattered.

That same generosity of spirit defined his family life. Don became a father and grandfather not only to his own children and grandchildren, but to a wide circle who considered him a father in every way that mattered. He met people where they were, accepted them without judgment, and tailored his guidance to what each person needed and could receive. When someone faced a problem, Don didn’t simply tell them what to do; he stayed beside them and helped them find a way forward.

To his family, he was the bedrock: the person who showed up, extended himself, opened worlds, and loved without conditions. He brought humor, brilliance, curiosity, and an unmistakable spirit of adventure to their lives.

Travel was one of Don’s abiding passions. His work and interests took him across Europe, Asia, Africa, North America, and beyond, and whenever possible, he brought his family along to experience the world with him. He retained a particular affection for France—especially Paris—and his travels left him with a lifetime of friendships, passport stamps, unforgettable meals, and great stories to tell. Among all the places he visited, however, Cabo San Lucas, Mexico, held a special place in his heart. There, Don and Sandy created a cherished second home, returning year after year to enjoy the sunshine, sea, and treasured time with family and friends.

Always close to Don’s heart were the New York Yankees. He and Sandy attended countless games together and were glued to games on TV when they couldn’t attend in person. Hardly a day passed without Don checking the score—or asking Sandy the score—of the latest game. The fortunes of the Bronx Bombers were woven into the rhythm of his daily life. When Don turned 60, Sandy gave him the gift of attending a Yankees Fantasy Camp, where he played alongside several former Yankees players.

Don and Sandy’s commitment to others extended well beyond their immediate family. For decades, they provided hands-on support to communities from New Haven to Haiti, another expression of the generosity and sense of responsibility that guided Don’s life. Don believed deeply in the power of education and opportunity. During his career at Pfizer, he designed a professional development program that brought business students from Florida A&M University to the company, providing them with mentorship, corporate experience, and a pathway to future careers. Don worked tirelessly to open doors for the next generation of leaders.

Don is survived by Sandy, his beloved wife; his children, David and his partner, Cesar Alexander Goza-Rivera; Mark and his partner, Dipa Mehta; Risë and her partner, Jonathan Jordan; his niece-daughter, Natasha Leigh Smith; his six grandchildren, Nikhil Nelson, Shivani Nelson, Seneca Burrow, Abiaraham Smith, Ajarano Smith-Bowe, and Akilah Young; and an extensive community of dear friends whom he loved as family. He was predeceased by his parents, the Rev. William Nelson and Lotta Nelson.

The family had the privilege of accompanying Don as far as we could in this life. Now, with profound gratitude for the love he gave us, the worlds he opened, and the countless lives he changed, we entrust him to God’s eternal care.

A Homegoing Celebration was held on Saturday, August 8, 2026, at St. Martin de Porres Church in New Haven, followed by burial at All Saints Cemetery in North Haven. In lieu of flowers, we kindly request that memorial donations be made to the Parkinson’s Foundation or to St. Martin de Porres Academy.