Dark Ops challenges are revealed as you earn them. They do not count toward percent complete. This list is a full list of all available Dark Ops challenges found in the Campaign, Multiplayer, and Zombies on Black Ops Cold War
Campaign

Retro Gamer
Unlock all arcade machines.
Reward: Calling Card

What Do the Numbers Mean?
Decrypt the Operation Chaos floppy disk.
Reward: Calling Card

Defiant
Attempt to jump to your death in Break on Through.
Reward: Calling Card

Antihero
Wipe out your former teammates using brute force in Ashes to Ashes.
Reward: Calling Card

Cover Your Tracks
Stash away five bodies as Belikov in Desperate Measures.
Reward: Calling Card

Awkward Chat
Answer Imran Zakhaev’s questions correctly in the elevator in Desperate Measures.
Reward: Calling Card

Dark Ops Master
Complete all Campaign Dark Ops challenges.
Reward: Calling Card
Multiplayer

Relentless Killer
Earn 10 Relentless medals (20 kills without dying).
Rewards: 5,000 XP and Calling Card

Brutal Killer
Earn a Brutal medal (25 kills without dying).
Rewards: 5,000 XP and Calling Card

Nuclear Killer
Earn a Nuclear medal (30 kills without dying).
Rewards: 5,000 XP and Calling Card

Frenzy Killer
Earn a Frenzy Kill medal (5 rapid kills).
Rewards: 5,000 XP and Calling Card

Mega Killer
Get a Mega Kill medal (6 rapid kills).
Rewards: 10,000 XP and Calling Card

Ultra Killer
Get an Ultra Kill medal (7 rapid kills).
Rewards: 10,000 XP and Calling Card

Chain Killer
Get a Kill Chain (killed more than 7 players rapidly).
Rewards: 10,000 XP and Calling Card

From the Depths
Get 25 kills against enemies that are on land or a ship’s surface when you are shooting at them from underwater with a primary or secondary weapon.
Rewards: 5,000 XP and Calling Card

Hard Wipe
Single handedly eliminate an entire squad of 4 players in a Fireteam mode.
Rewards: 5,000 XP and Calling Card

Back At You
Throw a Frag Grenade back and kill the enemy that threw the grenade at you.
Rewards: 1,000 XP and Calling Card

Nuked Out
Earned a Nuclear medal in Free-For-All without using Scorestreak rewards.
Rewards: 5,000 XP and Calling Card

Very Nuclear
Earn a Nuclear medal with 21 different weapons with all kills coming from that weapon.
Rewards: 5,000 XP and Calling Card

Underwater Ops
While underwater, plant C4 on an enemy occupied Gunboat or Wakerunner and detonate to destroy the vehicle and kill the occupants 5 times.
Rewards: 5,000 XP and Calling Card

Dark Ops Master
Complete all Multiplayer Dark Ops challenges.
Rewards: 10,000 XP and Calling Card
Zombies

Reaper of the Undead
Kill 1,000,000 enemies.
Rewards: 10,000 XP and Calling Card

Armed to the Teeth
Have 2 fully Packed Weapons with Ammo Mods equipped and 6 Perks active.
Rewards: 1,000 XP and Calling Card

Social Distancing
Reach Round 20 without being hit.
Rewards: 5,000 XP and Calling Card

The Anvil
Exfil a game with only using melee attacks.
Rewards: 5,000 XP and Calling Card

Another Round?
Reach Round 100.
Rewards: 10,000 XP and Calling Card

Good Enough
Reach Round 20 with only your starting load out and no upgrades.
Rewards: 10,000 XP and Calling Card

Invincible
Reach Round 30 without going down.
Rewards: 10,000 XP and Calling Card

Checkmate
Play every single trial in Die Maschine in a single game.
Rewards: 10,000 XP and Calling Card

Harbinger of Doom
Kill 50 enemies with a single support.
Rewards: 5,000 XP and Calling Card

Evil Unleashed
Complete the Main Quest in Die Maschine.
Rewards: 5,000 XP and Calling Card

Box Addict
Buy every weapon from the Mystery Box in a single game.
Rewards: 5,000 XP and Calling Card

King of Silverbacks
In Dead Ops Arcade, earn a cumulative high score of 999,999,999.
Rewards: 5,000 XP and Calling Card

Pristine Pelt
In Dead Ops Arcade, defeat Mamaback in the final round without ever dying.
Rewards: 5,000 XP and Calling Card

Dark Ops Master
Complete 11 Dark Ops challenges in Zombies.
Rewards: 10,000 XP and Calling Card