Here is the full list of all 32 Gladiator Guild Manager achievements.
Killed 2000 enemies
Killed Frost Mountain Spider boss
Won 1 vs Many battle in Ring of Death arena
Completed the Hollow Mountain Arena
Helped Baroness handle the mysterious undead situation at Hollow Mountain
Built a team of 10 gladiators
Killed Undead Yeti boss
Paid 200 gold of gladiator wages in one month
Started a successful undead pet shop business
Had one gladiator die 10 times
Killed Troll boss
Killed 50 enemies with one gladiator
Reached Adored reputation with any of the factions
Killed Ancient Undead boss
Killed 20 enemies with one gladiator
Had one gladiator fight in 20 battles
Killed first 20 enemies
Killed 100 enemies
Killed 500 enemies
Completed the first arena: The Graveyard
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 Clawbane boss
Sponsored bandits musical band
Joined a witch-burning council
Helped peasants gain better living standard
Helped High Necromancer to raise and send a small army of undead at Iron Town
Bought undead pets and kept them in your guild
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
Made a deal with peasants to sneak out gold from the Ancient Temple behind the Baronesses back