jeopardizer
One who imperils
One who jeopardizes—puts something at risk or in danger.
The word is rare, since English usually handles this concept with phrases: the person who jeopardized the mission rather than the jeopardizer of the mission.
When it does appear, it often carries a tone of blame or accusation.
One who threatens safety
- risk-takerOne who courts peril
- menaceSource of potential harm
- compromiserOne who yields partially
- underminerOne who weakens covertly
destabilizer · saboteur · wrecker · liability · loose cannon
One who deliberately undermines
- underminerOne who weakens covertly
- wreckerVehicle that removes others
- spoilerPremature ending disclosure
- subverterOne who overthrows
obstructor · betrayer · double-crosser · infiltrator · mole · turncoat · traitor · quisling
One who courts peril
- gamblerOne who bets
- speculatorOne wagering on outcomes
- daredevilReckless risk-taker
- adventurerOne pursuing exciting exploits
thrill-seeker · high-roller · plunger · punter · bettor · wild-card · maverick · hothead
endangerer
One who threatens safety
- risk-takerOne who courts peril
- menaceSource of potential harm
- compromiserOne who yields partially
underminer · destabilizer · saboteur · wrecker · liability · loose cannon
saboteur
One who deliberately undermines
- underminerOne who weakens covertly
- wreckerVehicle that removes others
- spoilerPremature ending disclosure
subverter · obstructor · betrayer · double-crosser · infiltrator · mole · turncoat · traitor · quisling · backstabber
risk-taker
One who courts peril
- gamblerOne who bets
- speculatorOne wagering on outcomes
- daredevilReckless risk-taker
adventurer · thrill-seeker · high-roller · plunger · punter · bettor · wild-card · maverick · hothead
jeopardizerpreserver
One that maintains or saves
saver · rescuer · conservator · maintainer · sustainer