It feels like a lot of people in this thread are seriously not thinking outside the box for this spell. You can't just think in terms of, "What other combat spells can I cast?" or "How can I damage people with this?" It has far more context-sensitive utility.

• You can simply walk past an entire encounter and lock the magic door behind you.
• When facing the lich, you can stop time to find and potentially begin destroying their phylactery.
• If you're surprised, you can buff yourself and set up magical traps to shape the battlefield.
• What if you have to manipulate the environment in some way in order to kill the BBEG, like ignite four braziers or draw special sigils? You can do that without the BBEG stopping you.

There's a lot of potential for this spell. But also, as I say a lot on these comment threads, please do remember that spells are just as much for the DM as they are for players. If you don't like this spell, don't use it. I'll happily have an archmage destroy you with it ;)

This requires some prep-work but will literally kill anything that dies when it has 0 hp.

Prepwork: Make a demi-plane and layer it with glyph of warding, symbol and other trap like spells, with as trigger a door opened by the knock spell. Fill demi-plane until you believe that you have enough traps such that even if the make a some of the saves they still die, have the glyphs and symbols close enough by the door so that if it is opened they reach outside. Works best with symbol. With some downtime and access to enough diamonds and or a wish spell, you should easily make it such that nothing can survive the traps.

When you encounter something that you absolutely must destroy, e.g. a Tarrasque. Cast time stop, cast demi-plane with the door near you target, cast knock on door, use any remaining turns how you like. When timestop ends, all traps will trigger and they should kill anything near the door opening.

just cast Time Stop and twinned spell to let two people be time stopped

Quote from DiceFarmer >>

You could cast cloudkill just outside forcecage, then let gravity or wind move it into the cage when time resumes.  Although I suppose that depends on whether you count the cloud itself as a spell, or the effect of a spell. 

Alternatively: Timestop > use  telekinesis to move 1000 lbs boulder 10 ft above target's head. ...then, for good measure, an 8th level fireball just beneath their feet as you release the boulder.

In any event, time stop may have sub-optimal use in combat for a ninth-level spell (see meteor swarm for when you absolutely, positively, need to Wreck-It!™ right the heck now), but it's still incredibly cool.  Depending on how lenient your DM is, I see this spell having all sorts of hi-jinks opportunities outside combat.  My sorcerer would use it just to place hats just above people's heads

 hats on heads defo worth a 9th level spell slot

It has a range of self... So unless you slit yourself it still doesn't work

Muda muda muda muda muda muda muda muda muda muda muda muda muda muda

Behold the WWOOORRRRLLLLLDDDDDD!

*DIO Intensifies*

Quote from IainWhinnery >>

Behold the WWOOORRRRLLLLLDDDDDD!

 Stinky dub watcher

When Za Waurdo is in D&D! 😮

My DM ruled that if you know Time Stop you can cast it as a reaction to someone else casting so that you are unaffected. It's completely inspired by JoJo and a massive waste of a 9th level spell slot in doing so, but it's funny to see the BBEG cast this thinking they're getting away only to get a Fireball in the face.

The idea was that since you've both cast Time Stop you both aren't frozen so damaging / effecting each other wouldn't stop the spells from functioning.

Become a sorcerer with gear magic, and ZA WARUDO

KONO DIO DA

I think time stop is a spell best used as a combination set up. Cloudkill is good since it cannot effect a creature until their turn (as confirmed by the lich in PotA using this combo on the players). You can also combine it with a pre cast of the invulnerability spell and contingency. Cast contingency on yourself with invulnerability the night before to then trigger when you cast time stop. You can then also bring up fire shield, mirror image, (armour of agathys if you use magic initiate to pick it up). There's a lot of options.

Quote from Patar >>

I think time stop is a spell best used as a combination set up. Cloudkill is good since it cannot effect a creature until their turn (as confirmed by the lich in PotA using this combo on the players). You can also combine it with a pre cast of the invulnerability spell and contingency. Cast contingency on yourself with invulnerability the night before to then trigger when you cast time stop. You can then also bring up fire shield, mirror image, (armour of agathys if you use magic initiate to pick it up). There's a lot of options.

 As fun as that sounds, contingency can't be combined with a spell higher than 5th level. Also, invulnerability and cloudkill are both concentration spells. Concentration is the worst limitation on time stop.

I once used Time Stop to be truly evil.

My party was fighting an Archmage and they were well prepared for the fight, until one of them hit 0 hit points and fell unconcious.

I let the Archmage cast Time Stop to buff up and all that, and then slowly walk to the fallen player and slowly sink a dagger in his eye socket to prevent one of the PC´s to heal him.

Za warudo! Toki wo tomare!

Quote from Furujiru >>

Quote from prof_narwhal64 >>

I can't wait to stop time, pick somebody up, and move them two steps down the stairs they are climbing right before I go back up the stairs and pose.

 Would not work:
"This spell ends if one of the actions you use during this period, or any effects that you create during this period, affects a creature other than you or an object being worn or carried by someone other than you."

Picking someone up and moving them definitely counts as an action that affects a creature other than you. 

 it a joke

Jojo reference

"You stop time, allowing yourself to take multiple actions in a row."

Oh wow, this could be very useful, maybe even OP...

"If you affect another creature or objects they are carrying, the spell ends."

Oh.