Kevin MacDonald has called time on his 17-year association with Aston Villa.
The 51-year-old has been in charge of Aston Villa's academy and reserve sides for nearly two decades, as well as being thrust into a first-team caretaker role following the departure of Martin O'Neill as manager in 2010.
Since his arrival in 1995, the Scot has overseen the development of players such as England internationals Gareth Barry, Gary Cahill and Gabriel Agbonlahor.
MacDonald's decision to leave Villa Park comes days after the appointment of new boss Paul Lambert, who is expected to bring in his own backroom staff to work at the club.
The Scot told the club's official website: "I've had an incredible 17 years at Aston Villa, one of the biggest clubs in the country, and wish to thank all the staff and players I have worked with during my time at the club.
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"I wish Aston Villa every success in the future."
Chief executive Paul Faulkner added: "As a club, we are immensely grateful for the contribution Kevin has made in more than 17 years at Villa.
"He has been an integral part of the success we have enjoyed at academy and reserve team level and, in assuming his caretaker responsibilities at the beginning of the 2010-11 season, he cemented his position as a man who will always command respect at this club.
"The whole of Aston Villa Football Club will wish Kevin well."