I'm not sure about this but I believe there is nothing in 5e that has an effect and also prevents or gives no save. To clarify, the verbiage is usually something along the lines of "Automatically Fail Save" rather than gets no save. 

You folks know what I'm talking about so don't jump in with your weapon attacks and magic missiles. So is there  a spell or some such that prevents or gives no save?

Do you mean like Power Word Kill where the spell just hits you with no attack, no save, or anything? If so, there are a few spells that work like that, but they are definitely the exceptions to the norm.

 Sleep has no save. If they're under the number of hp you roll to affect, they go to sleep.

AFAIK there is no spell that calls for an automatically failed saves. Spells that call for STR or DEX saves cast on stunned targets result in an auto fail, but that's the effect of the condition, not of the spell. Other spells like Sleep and Power Word Kill (as mentioned above) don't even call for a save, they just happen if the conditions are met.

Another for the list, Otto's Irresistible Dance has no save for the initial effect, though you can use your action to make a save against it after that.

To be clear, your branching off of this discussion correct?

https://www.dndbeyond.com/forums/dungeons-dragons-discussion/rules-game-mechanics/45676-what-happens-when-you-automatically-make-a-save

And are looking for a situation where a rogue with evasion could not avoid a careful spell fireball, right?

If so, I got not nothing. Something would need to take the save away from the spell, and nothing does.

For my list I only factored spells that did something negative or could be significantly unwanted. I therefore did not include healing spells, making them invisible or such as because they're completely positive things. I also did not include illusions like Major Image, 

• Armor of Agathys - unsure if it counts as target is self, but anyone damaging you takes damage with no save.
• Awaken - can be used on some creatures without offering any save or resistance, even if they're unwilling. Not sure why they'd resist but some might have preferred the way they were, and that creature even after awakening is charmed by you, without save or opportunity to resist, and after the charm they remain awakened, whether they like it or not, forever.
• Cloud of Daggers - Every turn damages a creature with no save.
• Color Spray - goes off HP
• Forbiddance - The chosen types of creatures in the chosen area take 5d10 damage every turn with no save.
• Forcecage - just including this because the Cha save is only for teleporting/planar travel, if they cannot teleport then you succeed at trapping them and they get no chance to avoid it (unless they Counterspell you, etc). DOesn't require concentration. Only 7th level so you can easily multiclass 2 levels fighter for an Action Surge. You could cast an AoE with a long duration, then cast this, all on the same turn and if the target cannot teleport out they're royally screwed.
• Gate - can be used to summon a creature from another plane to you, whether it wants to be summoned or not and cannot resist or prevent it.
• Gift of Gab - affects memories of everyone around you, within 5 ft (which makes the spell freakin' pointless but whatever), with no save.
• Heat Metal - If wearing or touching metal it damages them, no save, and only makes a Con save if the metal item is being held to avoid dropping it if they want to hold it. However, armour, for example cannot be dropped, so the target gets damage every turn, no save, for as long as they wear it and metal armour takes several minutes to remove...
• Hex - You place a curse on a creature and there's no save against it.
• Hunter's Mark - You magically mark a creature without them being able to save against it.
• Magic Missile - Damages creature without attack or save.
• Maze - Sends target to a maze in a demiplane, no saves. They have to make an Int check, DC 20, to escape.
• Otto's Irresistible Dance - Immediately affects target without any saves. To make a save target must use their actions.
• Power Word Kill - Goes off HP, no saved.
• Power Word Pain - Partly goes off HP for immediate effect but con saves to resist at end of turn. However, it does apply full affect for their turn immediately without save, so worth a mention.
• Power Word Stun - same deal as Pain one above.
• Scrying - OK this does have a save BUT it's possible to impose a -15 penalty to their save which cause many lower level creatures to auto-fail (let's say your DC is 15, that means the target has to have a +10 save bonus or they auto-fail.
• Sending - Puts a message in somebody's head whether they like it or not. Spam-cast in fake accents for maximum annoyance. Bonus points if you catch them in the middle of a speech or song or something breaking their rhythm and making them mess up.
• Shadow of Moil - damages any creature that hits you, no save.
• Sleep - goes off HP.
• Soul Cage - Enslaves the soul for a short while which has no way to resist.
• Wall of Force - Can be used to make a dome or box around a creature, tapping it, with it having no option to resist or save against this.
• Wall of Sand - You can create the wall even in spaces occupied by creatures, and creatures in the space of the wall are blinded, no save.
• Wish - Depending on the wish made on the target you can cause something bad to happen to them without any save. "I wish that the next creature to hurt me will receive all the effects of having drawn The Void card from the legendary magic item known as a Deck of Many Things."

Cyb3rM1nd you are the man.

Quote from DxJxC >>

To be clear, your branching off of this discussion correct?

https://www.dndbeyond.com/forums/dungeons-dragons-discussion/rules-game-mechanics/45676-what-happens-when-you-automatically-make-a-save

And are looking for a situation where a rogue with evasion could not avoid a careful spell fireball, right?

If so, I got not nothing. Something would need to take the save away from the spell, and nothing does.

 Not the entire conversation. I got to thinking whether there was anything out there that would cancel out Evasion. RAW says a paralyzed, petrified, dead rogue gets a save, even if fluff says he shouldn't.

Quote from Wysperra >>

Quote from DxJxC >>

To be clear, your branching off of this discussion correct?

https://www.dndbeyond.com/forums/dungeons-dragons-discussion/rules-game-mechanics/45676-what-happens-when-you-automatically-make-a-save

And are looking for a situation where a rogue with evasion could not avoid a careful spell fireball, right?

If so, I got not nothing. Something would need to take the save away from the spell, and nothing does.

 Not the entire conversation. I got to thinking whether there was anything out there that would cancel out Evasion. RAW says a paralyzed, petrified, dead rogue gets a save, even if fluff says he shouldn't.

 It is true (and weird) for paralyzed, petrified, stunned, and unconscious rogues with evasion to only take half damage, dead rogues don't have any class features. A corpse is an object.