Darwin Gross (1928–2008) was an American spiritual teacher who succeeded to the leadership of Eckankar in 1971 at the death of its founder Paul Twitchell. Gross officially took up the position of "Living ECK Master" on October 22, 1971 and appointed his successor Harold Klemp as Living ECK Master on October 22, 1981, though Gross later claimed Klemp failed to fully succeed to the position. Gross claimed to continue afterwards as the Living Eck Master, though he was precluded from continuing to use the Eck terminology.
Darwin Gross was born in 1928 in Denhoff, North Dakota. He was brought up in the Mennonite faith. As a young man, he served with the US 11th Airborne Division in Japan following World War II. Later, Gross worked as an engineer, acquiring gigs on the side as a jazz musician. He described in his books a childhood filled with encounters and learning from many of the spiritual teachers of Eckankar. The moment he found the writings of Paul Twitchell, he recognized this as the same teaching he had been receiving inwardly since childhood. He began studying Twitchell's mail-order discourses and soon wrote to Twitchell asking how he could help set up classes in the Portland, Oregon, area where he lived. Twitchell wrote back in November 1969, encouraging Gross to start some of the first ECK Satsang classes in the Northwestern United States. Gross continued taking on greater responsibilities with Eckankar and on many occasions traveled with Paul Twitchell to Eckankar Seminars. Gross gained the Eckankar title of leadership, the "Living ECK Master", upon Twitchell's death in October 1971.
On October 22, 1981, Darwin Gross's health problems led him to publicly appoint Harold Klemp as the Living ECK Master. Gross retained management responsibilities, running the corporate organization of Eckankar until 1983. In 1983 Gross was voted out of his position by the Eckankar Board of Directors under controversial circumstances involving unproven charges that he misappropriated Eckankar corporate funds. As Klemp entered an exclusive leadership role, the Eckankar corporate structure was changed in the State of California. This gave Klemp new authority in leadership as the only voting member of the Eckankar corporation. This change, considered by Gross as a "hostile takeover" of the corporation, was formally filed in the State of California on June 20, 1985. The policies giving Klemp exclusive powers were changed in Eckankar's Minnesota corporate papers on January 30, 1987, and were also changed in the Eckankar Nevada corporate papers on December 21, 1987.
Following the rift in ECKANKAR leadership in 1983, most members of Eckankar chose to follow Harold Klemp, but a number joined Darwin Gross and continue to learn under his new organization: "ATOM: Ancient Teachings of the Masters,"  in which he claimed to carry on the original teachings of Paul Twitchell.
In 1988, "The John Ankerberg Show" interviewed Gross in reference to his continued use of the term "Mahanta" (the inner spiritual master revered in Eckankar), and he said, "I always looked at myself as not the Mahanta but a vehicle for it."
Gross died on March 8, 2008 at the age of 80. According to the ATOM website, "Darwin’s Living Trust provides that his writings, music and unpublished works shall be held in trust to carry on his memory and life’s work as well as his predecessor’s, Paul Twitchell. The Teachings will continue to be made available to those who are interested in this most direct path to God."
During the decade of his leadership of Eckankar, Gross expanded the physical organization and membership of Eckankar substantially. His leadership was considered important for the followers of Eckankar during the time, prior to his 1983 expulsion from Eckankar.
Current ATOM students of Darwin Gross, who still study his discourses and books, consider Gross to be a very ancient master. Gross, like his teacher Paul Twitchell - the originator of Eckankar, is regarded as a spiritual master who descended from an ancient and direct line extending into a history that is said to predate the early history and existence of our planet and solar system. The mythology of the ECK Masters is outlined in Twitchell's The Spiritual Notebook.
Books by Darwin Gross in Eckankar
- Consciousness: The Key to Life, Menlo Park: IWP. (Out-of-print.)
- The Eckankar Area Representative’s Handbook, Menlo Park: Eckankar. (Out-of-print.)
- Eckankar: A Way of Life, Menlo Park: Eckankar. (Out-of-print.)
- From Heaven to the Prairie, Menlo Park: IWP. Autobiography. (Out-of-print.)
- Gems of Soul, Menlo Park: IWP. (Out-of-print.)
- The Way of Eckankar, Menlo Park: Eckankar. (Out-of-print.)
- Your Right to Know, Menlo Park: IWP. (Out-of-print.)
Books by Darwin Gross after Eckankar
- The Atom, ATOM.
- The Atom Way of Life, ATOM.
- Awakened Imagination, SOS.
- Consciousness Is Life, ATOM.
- Forbidden Knowledge, ATOM.
- The Power of Awareness.
- You Can’t Turn Back, SOS.
- "Your Right To Choose", ATOM
Books about Darwin Gross
- Burlin, Bernadine. Hero: Personal Experiences with Darwin Gross, ATOM.
- Burlin, Bernadine. My ECK Master Affair, Menlo Park: IWP. (Out-of-print.)
- Hammond, Alan. A Gift from the Master, Menlo Park: IWP. (Out-of-print.)