Mark Vaughan Gregg, age 80, of Red Oak, Iowa, passed away on February 13, 2026, at Methodist Jennie Edmundson Hospital in Council Bluffs, Iowa.

Mark was born on March 5, 1945, in Denver, Colorado, to Mark Pulliam Gregg and Novella Vaughan Gregg. He was raised in Prospect Valley, Johnstown, and Loveland, Colorado, graduating from Loveland High School in 1963. From an early age, Mark was immersed in farm life and developed a love for horses, outdoors, and the rhythms of rural life.

When Mark was young, his father passed away. A few years later, his mother married Lowell Myers of Loveland, who, alongside Novella, had a steady and meaningful influence on his life.

Mark attended Cornell College in Mount Vernon, Iowa, and later earned his degree in accounting from Fort Lewis College in Durango, Colorado. During his college summers, he worked as a wrangler at the Sombrero Ranch and YMCA of the Rockies horse stables in Estes Park, Colorado — a job that perfectly blended his love of horses and the outdoors. The YMCA is also where he met his first wife, Kathleen.

Following graduation, Mark began his career with Haskins & Sells in Denver, Colorado. After earning his CPA license, he returned to Loveland and established his own accounting practice. During this season of life, he also served as a volunteer firefighter and Lieutenant with the Loveland Fire Department, Rotary International, and the United Methodist Church, reflecting his lifelong commitment to service.

Mark later purchased The Lazy T Motel in Estes Park, Colorado, enjoying the challenges and rewards of small business ownership. While working at Fisher Hunt CPA, he met his future wife — and fellow accountant — Diane.

Mark and Diane were married on October 31, 1981, blending their families and beginning a remarkable partnership that would define the rest of his life. Soon after, they moved to Arizona, where Mark began a career in corporate accounting with Rural Metro Fire Department, serving as Chief Financial Officer and later Vice President. For a brief entrepreneurial chapter, Mark and Diane operated a landscape company before he returned to corporate leadership with American Medical Response (AMR) in Portland, Oregon.

Throughout his career with AMR, Mark and Diane lived in Arizona, Oregon, Pennsylvania, and Southern California. Wherever they resided, Mark continued to stay actively involved in Rotary International, building friendships and serving his community.

Family was the center of Mark’s life. Throughout their marriage, he and Diane delighted in watching their family grow with the addition of in-laws, grandchildren, and great-grandchildren. Their love, loyalty, and steadfast support for one another were legendary among those who knew them.

In 2005, Mark and Diane retired in Diane’s hometown of Red Oak, Iowa. Mark embraced small-town life, serving several years on the Red Oak City Council. He was a familiar and cherished presence at multiple local coffee groups and the Elks Lodge. The couple also treasured their winters at their second home in Sun Lakes, Arizona.

Mark was preceded in death by his parents, Mark and Novella; his stepfather, Lowell Myers; his beloved wife, Diane; grandson Harly Sellers; and several dear aunts and uncles.

He is survived by his children: David Bradley Gregg and wife Stephanie of Colorado; Shellie Diane Ruge and partner Tom Squires of Arizona; Mark Lowell Gregg and wife Bobbie of Oregon; Shad Sellers and wife Jennifer of Arizona; grandchildren David Jacob Gregg and wife Shelby; Angelina Gregg; Mark Austin Gregg and wife Brooke; and Sydney Flemmer and husband Isaac; Jax Sellers; and Ella Sellers as well as three great-grandchildren, extended family, and many treasured friends.

A Celebration of Life service will be held at 11:00 a.m. on Thursday, March 19, 2026, at LeRette Funeral Chapel in Red Oak, Iowa. Visitation with the family will take place one hour prior to the service. Burial will follow at Evergreen Cemetery in Red Oak, where Mark will be laid to rest alongside his beloved Diane.

Memorials are suggested to the First United Methodist Church in Red Oak, Iowa.