The 48-year-old has worked wonders with his country and is known to be well liked by his players.
But which ones could follow him to Sunderland, if he's appointed of course?
Craig Cathcart (Watford)
Sunderland have shipped the joint most goals in the Championship this season, and the addition of an experienced campaigner such as Catchart could help to shore things up at the back. The 28-year-old, who's won the vast majority of his international caps under O'Neill, is currently sidelined with a knee injury, although he could be back soon. A report in the Daily Mirror last month claimed Cathcart is not in Marco Silva's long-term plans at Watford.
Jordan Jones (Kilmarnock)
O'Neill gave Jones his international bow at the weekend, after the 23-year-old's impressive form for Kilmarnock. Sunderland aren't exactly short of wingers, although there's certainly room for one more. And Jones, a Middlesbrough native and former Smoggies player, could perhaps be tempted by a return to the north east.
Kyle Lafferty (Hearts)
Lewis Grabban and James Vaughan are essentially the same striker, and Lafferty's capture would add some much-needed variety up front. The 30-year-old has scored nine in 16 for an average Hearts team and boasts an impressive record at international level (20 in 63), too. He's under contract until 2019, but shouldn't cost the earth and would surely fancy a reunion with O'Neill.