During Character Creation, a class must be picked for your operative, which determines your starting perk as well as the initial position on the perk tree.
Operatives are able to select a second starting perk to become a hybrid class once they have enough perk points, which are obtained through leveling your character.
Thief[]
"As a professional infiltrator and con artist, the thief prefers to handle a job quietly. Thieves specialize in disguises and lockpicking. A good thief is an asset to any well planned silent mission."
- +50% disguise effectiveness
- Can pick locks
The Thief's initial perk is 
The Art of the Steal, which allows access to the Lockpick Kit, which can be used to pick the locks of certain doors. They are also adept at blending in, and disguises are more effective for this class. This is the only class capable of cracking safes without a code. This class is recommended to start with when doing stealth.
Lockpick Kit[]
The Lockpick Kit is a highly recommended tool for completing stealth missions. The Lockpick Kit can silently open any door without breaking the lock, which many other breaching tools will do. If an unlocked door is left open, a passing guard may notice and lock the door again depending on the mission you're playing, meaning you will need to unlock the door again.
Safe Cracking[]
The Thief also has another ability, safe cracking. This allows you to crack safes that typically contain items that are useful or required for mission completion. Safes can be cracked without any tools.
Thieves are capable of cracking safes in these missions:
Mercenary[]
"Mercenaries don't care how the job gets done, as long it gets finished. They specialize in all types of weapons. Precise, methodical, and deadly, you'll want a mercenary on your side when the bullets start flying."
- +40% health and stamina
- +1 Weapon Mastery perk
The Mercenary's initial perk is 
Combat Mastery, which increases their health and stamina by a fair amount and allows them to learn a second Weapon Mastery. It will also decrease the delay before stamina begins regenerating, as well as increase how fast it regenerates. Lastly, Mercenaries are the only class capable of intimidating Elite Guards in Concept. This class is recommended to start with if you prefer loud.
Engineer[]
"Engineers are the innovators of the crew. They specialize in enhanced equipment, explosives, and armor. Engineers can always offer a way past that door. Just don't ask them to do it quietly."
- Unlocks C4
- -40% armor movement penalty
The Engineer's starting perk is 
Demolitions Expert, which allows them to bring C4 into missions. Their training in armor mobility reduces the speed penalty from armor by a fair margin. They are also able to bypass sensors to allow their team to move through certain doors without being detected.
Engineers are capable of bypassing sensors in these missions:
Hacker[]
"Finding someone to hack systems is easy. Finding someone to hack systems while being shot at is... considerably harder. Hackers specialize in breaching computers and security systems on-site."
- Unlocks Keycard Scrambler
- Can hack advanced systems
The Hacker's initial perk is 
Prodigy, which unlocks the Keycard Scrambler, which can be used to open keycard doors. They are also capable of hacking computers to gain useful Intel. Additionally, they can take control of cameras to allow them and their team to view the map through the hacked cameras from outside of the camera room or router.
Keycard Scrambler[]
The keycard scrambler, as mentioned earlier, is mainly used to override keycard readers, opening them without the need of a keycard. This is typically very convenient, as normal getting a keycard will require getting lucky, or having to take out a significant number of NPCs, creating a lot of potential risk and wasting time. However, getting a keycard still isn't useless, as it is typically faster than using the scrambler, and using a keycard is only conspicuous, rather than suspicious. The keycard scrambler can also open time locks on Ryan's panic room door in The Financier, as well as the one for the server room door in The Lakehouse. Usually though, this isn't really a useful ability, as Ryan's panic room door can simply be blown up with C4, or ignored altogether by simply neutralizing Ryan before he gets there. The time lock for the server room door is also incredibly slow, taking 1 minute and 30 seconds to open if a scrambler is used, a highly significant amount of time considering that Legend difficulty has a time limit of just over 9 minutes on stealth.
Hacking Systems[]
The Hacker's most iconic ability, is of course, hacking systems. The Hacker is capable of hacking computers, which most commonly gives some intel, but may also do some other actions, such as luring an employee in The Withdrawal. Hacking is useful in almost every mission, granting a typically safer method for getting the safe intel in The Financier, getting the vault code and box ID in The Deposit, luring an employee in The Withdrawal, and much more.
Hackers are capable of hacking computers in these missions:
- The Killhouse
- The Auction
- The Financier
- The Deposit
- The Withdrawal
- The Scientist
- The SCRS
- Black Dusk
- The Lockup
- Concept
Hybrid Classes[]
By allocating a perk point into a second starting perk, an operative is able to become a new class with the standard abilities of both classes. A third or fourth starting perk cannot be selected. Hybrid classes are usually better than starter classes.
- Commando:
The Art of the Steal and Combat Mastery - Juggernaut: Combat Mastery and Demolitions Expert
- Technician: Demolitions Expert and Prodigy
- Infiltrator: Prodigy and The Art of the Steal
- Breacher: The Art of the Steal and Demolitions Expert
- Specialist: Combat Mastery and Prodigy