First Appearance Domina Tagge

In Star Wars #33, Baron Orman Tagge and his brother, Silas Tagge, are heading to a meeting with their younger brother and Imperial officer, Ulric Tagge, when Silas mentions another member of the family:

Silas Tagge: A veritable family reunion, Orman.  Pity our dear list sister doesn't have a role in our scheme.
Orman Tagge: Silas, your banter is not to extend to her.  Ever.  Be content that this meeting should spell doom for the Rebel Alliance.

While not mentioned by name, Silas is referring to their sister, Domina Tagge, who would appear two issues later in Star Wars #35.

Star Wars #33a - Marvel Comics, U.S. (March 1980)
newsstand
1st mention of Domina Tagge

Star Wars #33b - Marvel Comics, U.S. (March 1980)
direct
1st mention of Domina Tagge

Star Wars #35 follows the defeat of the House of Tagge's plan to use the Omega Frost weapon to destroy the Rebel Fleet.  The story, Dark Lord's Gambit, opens with Darth Vader learning Luke Skywalker's name.  He then meets with Ulric Tagge and reveals he has recovered Orman and Silas Tagge unconscious but alive.  Ulric is next in line to be Baron and Darth Vader tells him if he cooperates, he will not revive his older brothers.  Meanwhile, Luke Skywalker is on patrol with Blue Squadron when they come across a ship being attacked by Imperial TIE Fighters.  The patrol chases off the TIE Fighters and escort the ship to the Rebel base on Yavin VI.  On the ship is Sister Domina, priestess in the Order of the Sacred Circle from the planet Monastery.  The Order of the Sacred Circle has a large following throughout the galaxy and she wants the Rebellion to send an envoy to Monastery to present their side before making a decision to side with the Empire or the Rebel Alliance in the galactic conflict.  Upon hearing that the Imperial envoy is Darth Vader, Luke insists he is sent on the mission and Domina favors this choice.  The Rebel council agrees to send Luke who escorts Sister Domina back to Monastery.  On the planet's surface, Luke and Domina are attacked by a Nightshrike which Luke slays as Darth Vader appears.  Luke barely controls his anger as Vader taunts him for his inexperience as a diplomat.  As Luke questions his being there, Domina assures him "In all the Rebel Alliance, only you can fulfill what must be done here.  I know this... as a priestess... as a woman!"  Darth Vader's true intentions and Domina's family are revealed on the final page:

Domina Tagge: You used the force to make that Nightshrike attack, Lord Vader... It will impress the more superstitious of our followers.  But weren't you afraid young Skywalker would expose it...?  My instincts as a priestess tell me he, too, is familiar with the Force.
Darth Vader: True.  But he is still a novice.  Worse yet... he is a romantic.  Your overtures to him play on that...  It confuses his thoughts and ultimately his abilities.
Domina Tagge: Strange.  My family placed me in the order so I could maintain my innocence... be free of the Galactic Empire's many intrigues.  Yet here I am, deep in an intruge of my own... ready to betray the order.
Darth Vader To avenge the death of two brothers... including the one you loved most.  Such desires often overwhelm everything else-- --particularly in a long, proud line like yours.
Domina Tagge: Yes.  Why else would i have allied myself with the man my brother, Baron Tagge, hated?  But for all you did against Orman, you weren't responsible for his death... Luke Skywalker was!

Darth Vader's devious corruption of the youngest Tagge family member shows just how sinister he can be.  Orman wanted to keep her innocent, so naturally Darth Vader taints her to get revenge on the House of Tagge for their ambitions to gain the Emperor's favor!  Now that is evil!

Domina Tagge is the first of many red haired females Luke would be romantically attracted to.

Star Wars #35a - Marvel Comics, U.S. (May 1980)
newsstand
1st appearance of Domina Tagge

Star Wars #35b - Marvel Comics, U.S. (May 1980)
direct
1st appearance of Domina Tagge

Domina Tagge has her first and only cover appearance in the following issue.  The cover depicts the scene from the story where Luke kills a creature which appears to attack Domina.  Red Queen Rising! is a fitting title for the story.  It shows Domina gain the title of All-High Priestess as she announce the Order of the Sacred Circle will not side with the Rebel Alliance.  Instead she proclaims that Darth Vader and Luke will duel in the Crystal Valley at sundown which was not part of Darth Vader's plan.  It turns out that she has been scheming to eliminate two House of Tagge rivals, Luke Skywalker and Darth Vader!

Star Wars #36a - Marvel Comics, U.S. (June 1980)
newsstand
1st cover appearance of Domina Tagge

Star Wars #36b - Marvel Comics, U.S. (June 1980)
direct
1st cover appearance of Domina Tagge

Domina Tagge only appears in two more issues during the original Marvel run, in Star Wars #37 and #50.  She also appears in Star Wars #108 which was published by Marvel in 2019.  Set in the legend's continuity, issue #108 is a followup to the story published in Star Wars #50 way back in 1981.