Here is the full list of all 32 Gladiator Guild Manager achievements.
Won 1 vs Many battle in Ring of Death arena
Completed the Hollow Mountain Arena
Killed 500 enemies
Killed Undead Yeti boss
Bought undead pets and kept them in your guild
Made a deal with peasants to sneak out gold from the Ancient Temple behind the Baronesses back
Killed Troll boss
Had one gladiator die 10 times
Paid 200 gold of gladiator wages in one month
Built a team of 10 gladiators
Joined a witch-burning council
Helped peasants gain better living standard
Reached Adored reputation with any of the factions
Killed 50 enemies with one gladiator
Killed 100 enemies
Killed 20 enemies with one gladiator
Completed the first arena: The Graveyard
Had one gladiator fight in 20 battles
Killed first 20 enemies
Killed 2000 enemies
Finished the game on Hard or higher difficulty with Perma-Death mode and Gold Compensation scale at 30% or lower.
Built a team of 20 gladiators
Killed Ancient Undead boss
Killed Clawbane boss
Killed Frost Mountain Spider boss
Started a successful undead pet shop business
Sponsored bandits musical band
Helped High Necromancer to raise and send a small army of undead at Iron Town
Helped Baroness handle the mysterious undead situation at Hollow Mountain
Won gold by holding onto the pull-up bar for two minutes while visiting the traveling fair
Helped Baroness get taxes from the people without spilling any blood
Betrayed High Necromancer by standing on the side of the people at the court instead of defending him