Here is the full list of all 28 Space Hulk achievements.
Survive 15 close combat encounters
Escape with eight or more marines during “Decoy” mission
Cleanse both rooms in the same turn during “Cleanse And Burn” mission
Customize your banner
Kill 30 genestealers with the assault cannon
Kill 6 genestealers in one shot with the flamer
Kill 20 Genestealers with the power sword
Kill 6 genestealers with one psychic storm
Kill 5 Broodlords
Kill 1000 enemies
Kill 40 000 enemies
Win close assault against Broodlord
Destroy 20 doors with a Chainfist
Complete a mission without using a single Command Point
Unjam a bolter 40 times
Have a terminator kill 3 genestealers in melee during one turn
Survive “Suicide Mission” without any casualties
Kill 10 genestealers during one turn in the “Exterminate” mission
Pass the C.A.T. between at least three terminators during “Rescue” mission
Wake all unconscious Marines and take no casualties during “Alarm Call” mission
The marine that picks up the chalice in "The Artefact" mission must be the one exiting the map with it
Calistarius must survive "Escape Route" mission
Exit the map with at least 7 marines in the "Regroup" mission, but not before all have been put into play
Let no terminators die during "Defend" mission
Kill the broodlord in "Unknown Lifeforms" mission
Escape with at least two Terminators before the end of the tenth turn in "Pitfall" mission
Get all campaign achievements
Finish the “The Sin of Damnation” campaign