Dog Days
Dog Days was a summer-themed Tactical Alert in August of 2019.
Snowday Showdown
Snowday Showdown was a Christmas-themed Tactical Alert running in December 2016.
Long Shadow
Long Shadow was a Tactical Alert in late 2016 that saw the return of the Nightwatch Corps, last seen in Project Undermine.
One Thousand Cuts
The Tactical Alert One Thousand Cuts appeared in Hotfix 18.5.6. This was a series of new missions that appeared on Thursday and lasted until Monday.
Divine Will
The Divine Will Tactical Alert was a special mission on Venus that introduced the Razorback proxy.
Hallowed Nightmares
Hallowed Nightmares is a yearly Tactical Alert appearing around Halloween.
Project Undermine
Project Undermine was a Tactical Alert that saw the introduction of the Nightwatch Corps, as well as another run-in with the thief Maroo.
Emergency Exit
The Emergency Exit Tactical Alert was a special Alert mission where the Tenno protected two Bailiffs who were planning to defect from the Grineer.
Black Seed Scourge
The Black Seed Scourge Tactical Alert was a series of missions given to the Tenno by Frohd Bek, who was dealing with an offshoot of the Corpus known as the Black Seed.
Den of Kubrow
Den of Kubrow was a Tactical Alert in May of 2015, involving enhanced vampiric kubrow.