For this list, I'll be focusing on characters within the Legends continuity. Now, of course, there will be characters that are in the canon(Palpatine, Yoda, etc.), but I will include their feats within Legends. I will also look specifically at their power in the Force. Of course, my opinion can be changed as new Star Wars Lore comes and I'm not infallible, so the list might not be perfect.

1. The Bedlam Spirits

The Bedlams consist of four known members: Tilotny, Horliss-Horliss, Cold Danda Sine, and Splendid Ap. While it is debatable weather or not the Bedlams are Force users, there is no doubt they are powerful. They've been stated as omnipotent and capable of manipulating time and mass.

Feats/Accolades:

• Are omnipotent
• Could manipulate time and mass
• Can appear to be in multiple points in time and space at once
• Can change the physical forms of themselves and things around them
• Can bring people back to life
• Can drain the life of people

2. The Father

The number one spot should come as no surprise. He's been confirmed by Leland Chee as being the most powerful Force user to date, he's been implied to have defeated Abeloth and he's kept balance between the Daughter and the Son; two entities who, according to the Father, are capable of tearing apart the fabric of the Universe. He also appears to be nigh-omnipotent and various sources named him and his children as all powerful beings.

Feats/Accolades:

• Named the most powerful Force user in Star Wars History
• Suggested as being an all powerful deity
• Implied to have beaten Abeloth
• Kept balance between the Son and the Daughter
• Subdued the Son and Daughter various times with both telekinesis and lighting
• Has the ability to teleport
• Can manipulate a lightsaber with telekinesis casually
• Could change shape

3. The Son and the Daughter

Both the Daughter and the Son represent the different aspects of the Force. The Son was the very incarnation of the Dark Side, whereas the Daughter was the pure incarnation of the Light Side. Both are of equal power and both are constantly in conflict. They've been stated as being capable of tearing the fabric of the universe, and their mere presence could cause ripples and tumors in the Force and change the environment around them.

Feats/Accolades:

• They have the capability to tearing the fabric of the universe
• They are incarnations of the respective sides of the Force
• They've been suggested as beating Abeloth
• They have the capability to deflect lightsabers with telekinesis
• The Son could drain the life out of people
• The Daughter could heal and save lives of people
• They could change shape into a Griffin(Daughter) and Gargoyle(Son)
• They both know esoteric and powerful abilities
• The Son mastered lighting
• The Daughter mastered Tutaminis

4. Abeloth

Abeloth once found the ones of Mortis and became their servant. She soon loved them as if they were her own family so she was elevated as the Mother. But after she drank from the Font of Power and bathed in the Pool of Knowledge, she became corrupt with power. The Son and Daughter were taken a back by her sheer power and her evil spread as she became the spirit of Chaos. Imprisoned by the Father, Abeloth later came back and devastated worlds. She's been named the bringer of chaos and queen of the stars. She could form avatars in which she implants portions of her power so she could fool people around her and start chaos from the inside out.

Feats/Accolades:

• While weakened, she was described as having 12 times the strength in the Force Luke had
• She, while in her avatars, has fought people like Luke Skywalker, Krayt, Ben Skywalker and multiple others with ease
• Has the ability to teleport
• Manipulates lighting without even coming in physical contact with it
• Could trap Force users in a Force Stasis
• Drained Dyon Stadd
• Creating illusions that fooled Luke
• Can twist people's minds and turn them insane
• While weakened, she sends Luke Skywalker, Sarasu Taalon, Gavar Khai, Ben Skywalker and Vestara Khai flying with a Force Wave casually. The Force of the wave paralyzed Ben
• When a mere aspect of Abeloth was severely weakened and wounded, she unleashed energy that destroyed an entire City that caused people to turn inside out and to be ripped apart and melting buildings all around
• She injured Luke Skywalker with lighting

5. Waru

Waru is a trans-dimensional being capable of consuming and giving life to others. He apparently comes from a universe of his own and has mastered the art of the Anti-Force, being outside of the Force's perceptions.

Feats/Accolades:

• Capable of consuming and giving life
• Capable of healing incredible wounds and illnesses
• Telepathic communication and probing
• Put Luke's and Leia's mind in a trance
• Has the power to open trans-dimensional portals
• Has the power to destroy Luke Skywalker

6. The Force Priestesses

Similarly to the Bedlams, they lack general feats and appearances to suggest just how powerful they are. But they've been implied to be the first to unlock immortality in the Force through the Light Side and are seemingly guardians of what the light of the Force stands for. They also exist in a plain between the Living and Cosmic Force.

Feats/Accolades:

• They have knowledge of the greatest secrets of the Force
• They know how to unlock immortality in the Force
• They are seemingly guardians of the Light Side

7. Grandmaster Luke Skywalker

Luke Skywalker was the son of the Chosen One and thus inherited his father's potential and actually fulfilled it. He's been stated as being the most powerful Jedi of all time and that he had greater potential than Darth Sidious himself. He rebuilt the Jedi Order and was noted by George Lucas himself as being the most powerful being in the EU in regards to the Jedi and the Sith.

Feats/Accolades:

• Stated as having Anakin's potential
• Stated as having more potential than Emperor Palpatine/Darth Sidious
• Destroyed armies of Vong with a telekinetic wave
• Manipulated Proton Bombs via the Force casually
• Casually destroyed a mountain sized fortress, then rebuilt it, then crushed it again and scattered all of it's parts across seas
• Telekinetically manipulated a Black Hole
• Used telepathy to read the mind of an entire Solar System
• Placed an illusion into Caedus's mind that made Caedus flee
• Brought down an AT-AT

There is a lot more, but you understand the point.

8. Darth Sidious/Emperor Palpatine

There is no doubt about it that Darth Sidious is going to be on this list. He's been stated the most powerful Sith in modern times and later on the most powerful Sith Lord in history. Before his prime, he fought as an equal with someone as powerful as Grandmaster Yoda of all people. He later managed to find a way to cheat death via Essence Transfer and became the greatest incarnation of the Dark Side among mortals.

Feats/Accolades:

• Stated the most powerful Sith Lord ever
• Stalemated Grandmaster Yoda before his prime
• Passively Drained a planet the size of Byss
• Ragdolled Savage Opress and Darth Maul
• Choked Dooku from across the galaxy
• Nearly killed Sedriss with telekinesis
• Casually threw multiple senate pods
• He has casually mentally influenced Darth Vader from across the galaxy
• He has resisted the mental probes and scans of Shaak Ti and Saesee Tiin
• He stood in the middle of the entire Jedi Council and none could sense that he is Sith
• Has killed entire battalions with lighting while injured
• Has turned Dark Side prophets and various other people into skeletons, ash, husk and chard
• Has summoned Force Storms casually that ravaged the surfaces of entire planets and that could destroy moons and entire feats
• Used Essence Transfer to transfer his spirit into other bodies

Once again, there is a lot more, but you get the picture.

9. Emperor Valkorion

Emperor Vitiate was stated as the most powerful Sith Lord up to and during the time of his rain(which was during the Great Galactic War and post). So this places him canonically superior to Sith like Exar Kun, Darth Malgus, Naga Sadow, Ludo Kressh, Darth Nihilus, Darth Traya among many others. Later, after several apparent deaths, he has returned as the ruler of a new Empire in the form of Valkorion.

Feats/Accolades:

• Stated the most powerful Sith Lord in history up to and during the time of his rule
• Stomped Tol Braga's strike team
• While in a weakened state, he caused quakes and temples to collapse
• He's drained the planet of Ziost
• Has ragdolled Revan
• Has believed to be an embodiment of the Dark Side
• Corrupted the environment of Dromund Kaas
• Mastered Essence Transfer and found a way to cheat death
• One-shotted Arcann
• One-shotted Marr
• Destroyed fleets with Force Storms
• Has been called a Dark Side entity

10. Grandmaster Yoda

Yoda has been stated the second most powerful Jedi of all time and one of the most devastating foes to the Dark Side of the Force. He's trained many of the best Jedi(like Obi-Wan Kenobi and Luke Skywalker), and served during the described prime of the Jedi Order(up to that time). He's also fought as an equal with Darth Sidious during the time of Revenge of the Sith.

Feats/Accolades:

• Stated the second most powerful Jedi in history
• Stated the greatest foe to the Dark Side(other than Luke)
• Casually manipulated CIS transports
• Casually manipulated tanks
• Threw senate pods
• Caused avalanches
• While out of his prime of power, he easily moved an X-wing
• He easily manipulated Asajj's ship
• Sent entire armies back with telekinesis
• Suggested as knowing Force Light
• Named an elite Jedi
• Sensed multiple hidden Chameleon Droids
• Deflected Dooku's lighting with tutaminis
• Deflected Sidious's lighting with tutaminis
• Stalemated RotS Darth Sidious in a battle of the Force

Honorable mentions

• Darth Plagueis
• Darth Caedus
• Starkiller
• Darth Bane
• Darth Tenebrous
• Exar Kun
• Karness Muur
• Marka Ragnos
• Freedon Nadd
• Ajunta Pall
• Revan
• Darth Vader
• Darth Krayt
• Kyp Durron