Waldo (Super Stealth) (5e Optimized Character Build)
From D&D Wiki
Both of these Races give you a +2 to your Dexterity, they're fairly equal for optimization
Lightfoot Halfling use this race if you want to hide behind your fellow adventurers.
Wood Elf use this race if you want to hide in fog or small bushes.
Rogue (2 level minimum)
Choose Stealth as one of your Expertise to add double your proficiency bonus.
Cunning Action allows you to take the Hide action as a Bonus Action on your turn.
Ranger (10 level minimum)
When you gain 2nd level spells choose Pass Without Trace for a +10 to Stealth checks
At level 10 you gain Hide in Plain Sight this gives you a +10 to your Stealth checks so long as you don't move
[READER EDIT] - It's better to only take 2 or 3 levels of Ranger for Pass Without Trace and 11 levels of rogue because it makes it to where any skill that adds your proficiency bonus can't roll below a 10 which is significantly better than that plus 10 from Hide in Plain Sight because it prevents you from critical failing, and also has a higher minimum roll than with Hide in Plain Sight Optimized Build with this info - Variant Human, 11 levels Assassin Rogue, 3 levels Gloom-stalker Ranger, 6 levels Arcane Archer Fighter - This potentially lets you do tons of damage, and get the Lucky, Sharpshooter, and Alert feats to supplement initiative, stealth, and attacks. Just check out this build video to get a better understanding of the build above along with the modifications I made to it https://www.youtube.com/watch?v=JNlClZ-6ebA
you should always be using Cunning Action to hide after you've made an attack or used your action, unless the situation calls for something else.
+17 is normally good enough, but if you really need to disappear then use your action on round 1 to cast Pass Without Trace to gain the extra +10
Total Stealth Bonus (level 17+)
+10 (Pass Without Trace)
+10 (Hide in Plain Sight)*
- -Note you cannot use hide in plain sight for combat since it takes one minute to camouflage
Once you've raised you Dexterity to 20 it doesn't really matter what your do nobody will see you (you could even run around in full plate armour),
[READER EDIT] You can't wear plate armor. Your STR isn't 15.
[READER READER EDIT] If the Armor table shows “Str 13” or “Str 15” in the Strength column for an armor type, the armor reduces the wearer’s speed by 10 feet unless the wearer has a Strength score equal to or higher than the listed score. It DOES NOT prevent you from wearing such armor. [READER READER READER EDIT] If he's wearing mythril plate armor, he doesn't need to meet the strength requirement and it would not impose disadvantage on his stealth checks. [READER READER READER READER EDIT] Nowhere does it say his strength score. The 'For Added Fun' section does show a strength score of 8, it also says that those are the scores that they would personally use. But if you don't go for Wisdom, and use the standard array, you could put 15 in Strength and 14 (then +2 from elf or halfling) in Dexterity allowing you to wear normal plate armor without the loss to speed. And yes, you would have disadvantage on stealth, but with a bonus of +17 (without Pass Without Trace or Hide in Plain Sight) would mean that is minimum roll is a 19, without a natural 1. [READER READER READER READER READER EDIT] You can still roll 3d6 and get lucky with stats, getting some high stats and low stats like 15, 7, 10, 16, 9, 18, 12 at your disposal to choose from.
personally I'd go arcane trickster so you can make illusions to hide behind.
For Added Fun: I SEE EVERYTHING
If you chose Wood Elf as your starting race, and use the standard array, you can produce a character whose ability scores look like this:
Dexterity: 15 (then +2 from wood elf)
Wisdom: 14 (then +1 from wood elf)
You will need to use two Ability Increases to bring your Dex to 20, with an extra one point you can put in Wis, so now your Wis is 17 as well, if you put the next Ability Increase into Wis and use your final increase to get the Observant feat, you can raise your score to 20 as well. If you have proficiency in Perception, your bonus will by +11, fairly high, and with the Observant feat, your Passive Perception (your ability to notice things like NPCs/Monsters using stealth or hidden doors, paths, items, etc. without actively searching) will increase by 5 to a staggering 26, if you invest an Expertise in Perception, you will have +17 in Perception, and 32 Passive Perception.
tl;dr: Congratulations, not only can nothing see you, nothing can escape you sight.
- Note: these were the scores I personally used, you can use any combination you want as long as you have 17 Dex and 16 Wis.