From the humanoid ones, the midwives, most definitely. But the sheer terror of turning around ans seeing one of those swarm pods, just as they break up and release those bloody insects, gah! I run for my life like a maniac, hiding behind a corner, waiting for them to die..;)

Wow, and I have not even met the midwives yet... Monkeys used to creep me out when I played this game when it was new, but this time around they don't scare me at all. Never got far last time, but now I'll make it all the way!

I'm intrigued... Gonna play some more so I get to the midwives :)

The droids are the worst. Nothing more pants-shitting than coming around a corner and running directly into one.

Who chose these colors? I don't like them one bit.
Where did he go? Oh!
Right away sir! I'm sure this is just what you were looking for!
WAHHHWAHHHWAHHH *BOOM!*

You know what? I just saw the Rumbler's shoulders. There's a human head plainly visible on them. I think the scariest monsters are rumblers, now.

Spiders for me. (Arachnophobia)

Plus they're very hard to kill and do a hell lot of damage.

When I first played this when it came out, I was terrified by the protocol droids. Getting through the engineering cargo bays was one of the scariest gaming moments of my life. There would always be one of them spawning nearby or breaking out from a container as I went by; one of the little bastards was even responsible for the only time I ever screamed in horror in front of my screen as, after finishing exploring one of the bays, I turned around to get back and saw it RIGHT IN FRONT OF ME, completely silent -- there had been no walking noises, maybe a bug or an unfortunate respawn -- exploding me to bits as I almost fell from my chair.