Wigan have announced Uwe Rosler as their new manager after agreeing compensation with Brentford.
Marseille have parted company with manager Elie Baup in the wake of Friday's defeat to Nantes at the Stade Velodrome.
The former Republic of Ireland international has been out of management since leaving Al Ahli in April 2011.
He has been away from the game in England since seeing his contract at Aston Villa terminated by mutual consent in July 2006.
Prior to a stint at Villa Park, O'Leary had spent six years at Leeds - two as assistant to George Graham and four as manager.
He oversaw a productive period in the Whites' history, as they spent big chasing the dream and graced the semi-finals of the UEFA Champions League in 2000/01.
Reports have suggested that O'Leary is among those being considered to fill the managerial void at Elland Road created by Warnock's decision to quit the Championship club, and the 54-year-old has welcomed the rumours.
"I still live in the area and they (the supporters) have been absolutely fantastic," O'Leary said in the Yorkshire Evening Post.
"I'm very flattered that people remember me up there.
"I don't want to influence anyone but it wasn't my decision to leave and the supporters have always been there for me. That's why I've stayed in the area. It's a fantastic place to live."