The most fearsome, frightening monster in any RPG is...

[Semiurge]

Scavenger bot from Sword of the Stars: The Pit. Fucker could steal a random item from your inventory and run away with it. In a roguelike game, with very high randomness when it comes to drops. Even more scary is a bot that has a special ability to summon several of those. Basically if you saw one accompanied by a Very Dangerous Monster(tm) - you still targeted the bot first. That is what I call truly fearsome.

Fuckers always sneak behind you and run when you turn toward them

But they can't outrun guided missiles

 

[Taka-Haradin puolipeikko]

Scavenger bot from Sword of the Stars: The Pit. Fucker could steal a random item from your inventory and run away with it. In a roguelike game, with very high randomness when it comes to drops. Even more scary is a bot that has a special ability to summon several of those. Basically if you saw one accompanied by a Very Dangerous Monster(tm) - you still targeted the bot first. That is what I call truly fearsome.

Maintenance masters and their "spawn bunch of these bots just behind player's back" -mechanic is complete bullshit.

 

[luj1]

Radiation Angel

 

[Serus]

Scavenger bot from Sword of the Stars: The Pit. Fucker could steal a random item from your inventory and run away with it. In a roguelike game, with very high randomness when it comes to drops. Even more scary is a bot that has a special ability to summon several of those. Basically if you saw one accompanied by a Very Dangerous Monster(tm) - you still targeted the bot first. That is what I call truly fearsome.

Maintenance masters and their "spawn bunch of these bots just behind player's back" -mechanic is complete bullshit.

Might be, but the thread is about "fearsome" not "most bullshit" creatures and they were fearsome in my opinion, regardless of whether the mechanic was good or not.