The 28-year-old was released by Wolfsburg last season, having spent two seasons in Germany where he scored three times.
Bendtner began his career at Arsenal in 2005, spanning nine seasons, including three loan spells away from the Emirates.
A comedy figure for most football fans, Bendtner has been unable to reach the potential he had at Arsenal, where he was touted as a star. The striker scored 24 Premier League goals under Arsene Wenger, and famously wore the number 52 shirt after changing from his original number, 26. The maverick kindly offered to pay for fans to get new shirts if they had already purchased one with his name and number 26 on the back.
Having left the club in 2014, Bendtner could come back to haunt his former club, with Forest set to take on Arsenal in the next round of the EFL Cup.
That is now a very real fear for Gunners fans, who have reacted to Bendtner's potential homecoming on Twitter.
AFC_beej) September 7, 2016
Bendtner could face us in the EFL cup on September 20th. Looking forward to that. #AFC— Rabbi. (@Obiba_) September 7, 2016
Niklas Bendtner joins Nothingham Forest [2 year deal].— Arsène Cross♣ (@don_cross_AFC) September 7, 2016
You know he's gonna score against us in the EFL Cup.
Bendtner to Nottingham Forest?? Scenes when he knocks us out the Tin Pot Cup Whatever its called this week :D #AFC— Shaheen Ashraf (@topgooner100) September 6, 2016
Scenes when Bendtner scored the winner for Forest against Arsenal #afc— Bharat (@ManLikeXhakaa) September 6, 2016