Uqquz' Zekul-Mshqx was magically merged with Prince Keldor to create Skeletor.
Horde Lord was also the Father of Zodac Zur and Probably Emporer Anillis Kur, better known as Horde Prime.
Lord Nikolas Powers, also known as the Faceless One, was the father of Evelyn Morgana Powers, better known as Evil Lyn, whom he sent into the Future.
King D'Vann Grayskull's Father was also the Father of an Unnamed Son.
Lord Bryon of the House of Swann was the father of Queen Veena.
Prince Hec-Tor Kur, better known as Hordak was partially responsible for raising Princess Adora, after he kidnapped her as an infant.
Zodac Zur was revealed to also be a brother of Hordak, whom he was later killed by.
Emporer Anillis Kur, better known as Horde Prime, was the Elder brother of Hordak, and the father of Prince Zed.
The Unnamed Brother of King Grayskull was eaten by Snakemen.
King Grayskull and Queen Veena were the Ancestors of Prince Adam and Princess Adora. They had a son named Gray.
King Gray, also known as He-Ro is an ancestor of Prince Adam and Princess Adora. The identity of any children he may have had is unknown, but King Elden may be his earliest known descendant. Queen Xerxa is an Ancestor of Prince Adam and Princess Adora. The identity of any children she may have had is unknown, but King Elden may be her earliest known descendant.
King Elden was the father of King Valnar.
King Valnar was the father of King Freenorn.
King Freenorn was the father of Miro's Unnamed Grandfather.
Miro's Unnamed Grandfather was the father of Miro's Unnamed Father.
Miro's Unnamed Parents were the parents of King Miro and the Paternal Grandparents of King Randor.
Randor's Unnamed Maternal Grandparents were the parents of King Miro's Unnamed Wife and her Unnamed Sister.
Duncan's Unnamed Parents were also the parents of his Older brother, Malcom, better known as Fisto.
King Miro had his first child, Keldor, with Saryn a Gar Woman. He later had another 3 children with his Unnamed Wife; King Randor, King Stefen and an Unnamed Daughter.
Shakra, a Horde servant, was partially responsible for raising Princess Adora. Shakra's positive influence on her during her early years, helped instill a sense of goodness in Adora.
Queen Amaxa's Unnamed Mother is the sister of King Miro's Unnamed Wife, she is also possibly the mother of King Sullei and his sister The Prophetess.
Malcolm, better known as Fisto, is the probable father of Kay-La.
Duncan, the Man-At-Arms, is the Adopted Father of Teela.
In the Filmation Cartoon, Teela's Father was described as a great hero that died in battle.
Teela-Na, better known as the Sorceress, is the Mother of Teela.
Prince Keldor and Evelyn Morgana Powers had a Child, known as Skeleteen, who Evelyn sent into the future.
King Randor and Queen Marlena had twins, Prince Adam, also known as He-Man, and Princess Adora, also known as She-Ra.
King Stefen is the father of Prince Dal.
Miro's Unnamed Daughter is the mother of prince Michael and possibly the mother of Prince Jeremy.
King Sullei is possibly the father of Goras and Lady Edwina.
Queen Amaxa is possibly the mother of the twins Runalf and Yaine.
The Falcon is the father of Captain Jeoff Blithe, better known as Seahawk.

Prince Adam marries Teela and they have a son Prince Dare.
   
 
Masters of the Universe
 
Direct Relationship

Unsure Relationship

Unknown Generational Gap

Adoption

Raised

Time Travel Involved

Magically Melded With 		Uqquz' Zekul-Mshqx (Demo Man) Horde LordHordak's Unnamed Mother
Lord Nikolas Powers (The Faceless One)Nikolas' Unnamed Wife Grayskull's Unnamed FatherGrayskull's Unnamed Mother Lord Bryon of the House of SwannBryon's Unnamed Wife Prince Hec-Tor Kur (Hordak)Zodac ZurEmperor Anillis Kur (Horde Prime)
Grayskull's Unnamed BrotherKing D'Vann GrayskullQueen Veena Beatrix
SarynKing Gray / He-RoQueen Xerxa
King EldenElden's Unnamed Wife
King ValnarValnar's Unnamed Wife
King FreenornFreenorn's Unnamed Wife
Miro's Unnamed GrandfatherMiro's Unnamed Grandmother
Miro's Unnamed FatherMiro's Unnamed Mother Randor's Unnamed Maternal GrandfatherRandor's Unnamed Maternal Grandmother
Duncan's Unnamed FatherDuncan's Unnamed Mother King MiroMiro's Unnamed Wife Shakra Amaxa's Unnamed FatherAmaxa's Unnamed Mother
Malcolm's Unnamed Wife Malcom (Fisto) Duncan (Man-At-Arms) Teela's Unnamed Father Teela-Na (The Sorceress) Lady Evelyn Morgan Powers (Evil Lyn) Prince Keldor of the house of Miro (Skeletor) King Randor of the house of Miro Queen Marlena Glenn King Stefen Stefen's Unnamed Wife Royal Sister's Unnamed Husband Miro's Unnamed Daughter The Prophetess King Sullei Sullei's Unnamed Wife Amaxa's Unnamed Husband Queen Amaxa The Falcon Falcon's Unnamed Wife Anillis' Unnamed Wife
Kay-La Teela King Adam of the house of Randor (He-Man)Princess Adora of the house of Randor (She-Ra) Prince Dal Prince JeremyPrince Michael GorasLady Edwina RunalfYaine Captain Jeoff Blithe (Seahawk) Prince Zed
Unnamed Son of Keldor (Skeleteen) Prince Dare (He-Ro Son of He-Man)
Uqquz' Zekul-Mshqx / Demo Man (MOTUC)
Horde Lord (DC Comics)
Lord Nikolas Powers / Faceless One (MVC Comics) and (MYP Cartoon) and (MOTUC Bios)
Lord Bryon of the House of Swann (MVC Comics / Q&A)
Anillis Kur / Horde Prime (Filmation Cartoons) and (UK Comics) AND (MOTUC Bios)
Zodac Zur (Almost All Sources) and (DC Comics)
Hec-Tor Kur / Hordak (Almost All Sources)
Grayskull's Brother (MOTUC Bios)
King D'Vann Grayskull (MYP Cartoon)
Queen Veena (MYP Cartoon)
Beatrix / Light Spinner / Shadow Weaver (Almost All Sources) and (DC Comics)
Saryn (MOTUC Bios) and (MYP Cartoon / Q&A) and (DC Comics)
Prince Gray / He-Ro (MOTU Mini-Comics) and (DC Comics)
Queen Xerxa* (World I.P. Annuals Books)
King Elden (Filmation Cartoons)
King Valnar (Filmation Cartoons)
King Freenorn (Filmation Cartoons)
Miro's Grandfather (Filmation Cartoons)
Miro's Father (Filmation Cartoons)
King Miro (Filmation Cartoons) and (MYP Cartoon) and (MOTUC Bios)
Miro's Wife (MOTUC Mini-Comics)
Amaxa's Mother (World I.P. Annuals Books)
Shakra (Filmation Cartoons)
Malcom / Fisto (MYP Cartoon) and (MOTUC Bios)
Duncan / Man-At-Arms (Almost All Sources)
Teela's Father** (Filmation Cartoon) and (MYP Cartoon)
Teela-Na / Sorceress (Almost All Sources)
Lady Evelyn Morgan Powers / Evil Lyn (Almost All Sources)
Prince Keldor of the house of Miro / Skeletor (Minicomics / Q&A) and (MYP Cartoon / Q&A) and (MOTUC Bios)
King Randor of the house of Miro (Almost All Sources)
Queen Marlena Glenn (Almost All Sources)
King Stefen(Filmation Cartoons)
Royal Sister (World I.P. Annuals Books)
King Sullei* (World I.P. Annuals Books)
The Prophetess* (World I.P. Annuals Books)
Queen Amaxa (World I.P. Annuals Books)
The Falcon (She-Ra)
Kay-La* (He-Ro Son of He-man)
Teela (He-Ro Son of He-man) and (Almost All Sources)
King Adam of the House of Randor / He-Man (Almost All Sources)
Princess Adora of the House of Randor/ Captain Despara / She-Ra (Almost All Sources)
Prince Dal (Filmation Cartoons)
Prince Jeremy* (Filmation Cartoons)
Prince Michael (World I.P. Annuals Books)
Goras* (German Audio Plays)
Lady Edwina* (He-Man Filmation Cartoon)
Runalf* (Masters of the Universe Storybook)
Yaine* (Masters of the Universe Storybook)
Prince Zed (Filmation Cartoons)
Captain Jeoff Blithe / Seahawk (He-Ro Son of He-man) and (She-Ra)
Prince Deon / Skeleteen (MOTUC Bios / Q&A) and (MOTUC Mini-Comics)
Prince Dare / He-Ro*** (MOTUC) and (He-Ro Son of He-man)

*It is not fully known where on the family tree they belong, so I used my best guess.

**According to the Original Mini-comics and MOTUC Bios, Teela is a clone of Teela-Na created by Skeletor's Magic.
  Also according to MYP Q&A it was revealed that Teela's Father was going to be revealed as Fisto.
  In the Filmation Cartoon, Teela's Father was never revealed, but he was a great hero that died in battle.

***According to MOTUC Dare is the son of Adam and Teela.
  In the rejected He-Ro Son of He-Man Cartoon he was going to be Adora and Seahawk's real son and Adam's adopted son.

Special thanks to gbagok of the He-Man.org Forums for letting me use his artwork of
Lord Nikolas Powers and Lord Bryon of the House of Swann.

Special thanks to danbrenus of the He-Man.org Forums for letting me use his artwork of
Zodac Zur.