The Hoops bid farewell to Brendan Rodgers in February when the two-time Scottish Premiership winner walked away to take charge of Leicester City in the Premier League.
Lennon has done a fine job over the last two months, leading Celtic to the verge of a third successive domestic treble.
But it remains to be seen whether the club captain will be offered the job full-time.
According to the Mirror, Wagner is one potential alternative. The affable German certainly ticks a lot of boxes despite leaving Huddersfield Town when they were bottom of the Premier League table in January.
Wagner, who coached Borussia Dortmund’s reserves before he moved to Yorkshire, has a proven track record when it comes to promoting and developing young players while his high-pressing style and impressive man-management style has apparently impressed the Celtic chiefs.
However, Wagner’s stock fell somewhat during a dreadful first half of the 2018/19 season which paved the way for Huddersfield’s relegation.