Those Spiders From Mars were pretty big
(back in the day)
 
Of course it was all Ziggy's fault

Not as big as John's but plenty big enough Camel Spiders were very common in Arabia. At night if you approached one it would try to take cover in your shadow giving the impression it was coming for you.
 
Urban legend is one would always beat a scorpion in a fight and bating apparently took place. I never saw it myself but I have been told the scorpion always won.
 
 

Do tarantulas count?
 
As to scary spiders, I used to do maintenance for commercial buildings. I was checking the back doors of a shopping center space (brokers would leave them unlocked for some reason). I went to check one and felt something roll off the back of my hand. I looked down to see this strange bubbling black biomass about 2 inches across. It almost looked like an ant hill. When I got to looking at it I realized that it was a black widow with A SLEW of babies swarming around her. Considering they just fell about 3 feet, they could not have been happy. I certainly wasn't going to try to stomp them out. Knowing I would have to deal with them at some point or another, I went to the truck, got a can of WD40, and used it as a flame thrower. Luckily, it was still an unfinished space so nothing to catch fire. This was not the first or only time I dodged getting bit by a poisonous spider.
 
The one spider that surprised me more than others, I came across a spider in the garage. I'm 6'2" and about 250# and this little $**t (about an inch and a half in diameter including the length of the legs) was standing firm with the legs raised ready to attack. Later, I found out it was a Parson's spider. He lost that encounter but I have to admire it as he had some balls!

DrLumen
The one spider that surprised me more than others, I came across a spider in the garage. I'm 6'2" and about 250# and this little $**t (about an inch and a half in diameter including the length of the legs) was standing firm with the legs raised ready to attack. Later, I found out it was a Parson's spider. He lost that encounter but I have to admire it as he had some balls!

Actually, he was trying to convert you. 

A clown can be scarier than a spider or spiders (at least, in the book and first movie, IT was).
 

 
                                                  We ALL float down here, Georgie.

bapu
Those Spiders From Mars were pretty big
(back in the day)
 
Of course it was all Ziggy's fault

Bass player blaming the guitarist. 
 
Never heard that one before. 

outland144k
A clown can be scarier than a spider or spiders (at least, in the book and first movie, IT was).
 

 
                                                  We ALL float down here, Georgie.

 
I've never been able to take clowns seriously.

paulo
 
I've never been able to take clowns seriously.

That's insane.

Another story, re DrLumen's decision not to stomp them out...
 
Was doing my pharmacy thing behind a Rite Aid counter in Lincoln City, OR. About 2001.
 
Was new on the block and my veteran pharmacy tech suddenly got sever agitated over something. She started babbling hi speed to someone on the other side of the counter. Said I was the new pharmacist and was dying to meet her. The tech said she had to go to the bathroom and took off like a bat out of hell. I was being set up...
 
The lady was a pure nut case. Psycho **** fixated on every ailment known to humanity. Problem was that it wasn't her that was sick, it was her dog she projected everything on to. She would come to the pharmacy with the latest ailment for her dog and want over the counter medicines to give the dog as a suppository. She would load up with chemicals and head back to cram them up the dog's ass. Poor creature.
 
Would experience a cold shudder every time she showed up because there was a lunatic 30 minute minimum tirade ahead, and the customer is always right. Piss her off and you could be fired. Work piled up as you concentrated on the poor dog's ass.
 
About Hobo spiders. Last thing I would want to be bitten by. Same venom as the brown recluse. In nature, they strike and retreat as the bug is dissolved internally. The spider comes back a few minutes later for a tasty milkshake.
 
Does the same thing to humans. Gross disfigurations at best. Loss of limbs and death maybe. Cuts off circulation to the area and dissolves proteins for the next meal. Body part where the bite happened can rot off.
 
One day the lady came in and said she didn't feel too good. She dropped her pants in the middle of public and her legs had a couple hundred red bite marks.
 
She lived in a trailer with her dog. She saw spiders coming thru the floor. Checked under the trailer and there were several nests of Hobo's in the wood debris.
 
Her response was to rip up the floor boards. Stripped herself naked and went on a stomping spree.
 
First time she ever asked for something for herself and not for the dog.
We told her to get the hell to the ER immediately (for whatever they could do)
 
Never saw her again. Outcome was not too good.
 
John