Shoulder reconstructions have sidelined a pair of Hawks until early 2021.
In his comeback year from a broken left leg in 2019, Mitchell played through the season with soreness in his right shoulder after hurting it in training just before the Round 2 restart.
He ultimately made a successful return to finish in second place in the Peter Crimmins Medal, with teammate Jack Gunston claiming the honours this year.
Irishmen Nash will join Mitchell in rehab until they can both rejoin the Hawthorn squad early next year.
Moving into his fifth year at AFL level, the 22-year-old played only two matches this season and will look to get more exposure to senior footy in 2021.
Hawthorn physical performance manager Luke Boyd expects both players to begin training in early 2021.
“Like with a lot of footballers, Tom has had a grumbly shoulder joint for a number of years and it’s something he has managed well over his career,” Boyd told the club website.
“Both these surgeries were the type that could wait until the end of the season, which now gives the pair a good chunk of time to focus on their rehab
“Both Tom and Conor will require three-to-four months of rehab and should return to training after Christmas.”