Speed Channel said president Hunter Nickell is exiting the driver's seat at the motor-sports programmer, having grown to its current 84-million-subscriber reach under his reign since 2005.
He will finish several projects at Speed over the next few months and continue to explore opportunities within the Fox Sports Media Group, the channel said.
An interim replacement will be named shortly, the network said.
National Geographic Channels U.S., a joint venture that is also part of the Fox Networks realm, saw its longtime president, Steve Schiffman, step down in November. (Hill yielded oversight of the Nat Geo TV outlets in August to Fox veteran David Lyle.) Other executive changes also took place at those programmers.
In the release annoucing Nickell's resignation, Hill said: "It's unfortunate that Hunter is stepping away after all that he's done for Speed. He's a man of great character, a true gentleman and he's served Fox tirelessly for many years. Speaking for everyone at Fox and News Corp., his spirit and dedication will be missed."
Speed noted that under Nickell, the programmer increased its relationship with NASCAR and "added several high-profile events to its programming lineup, including the NASCAR Sprint All-Star Race, the NASCAR Hall of Fame Induction ceremonies and all three of the NASCAR post-season awards banquets. Nickell also generated increased Speed programming and marketing presence at every NASCAR Sprint Cup Series race on the circuit, giving Speed unmistakable leadership in on-site network visibility."
The release also noted "Nickell elevated motor sports news efforts at Speed, creating and expanding the Speed Center franchise and strengthening relationships with Formula One, AMA Supercross, Grand-Am and other major series. He oversaw the development and expansion of Speed digital efforts, the building of a state-of-the-art, high-definition studio in Charlotte, N.C., in 2008 and the launch of SPEED2, an authenticated broadband network, in 2010."
Nickell said in the release: "I worked with great people and awesome partners ... I am grateful and I have had a blast."
Nickell came to Speed in 2005 after 12 years as general manager of Fox's FSN South.