Based from the DC Comics character, Blackfire is the elder sister and archenemy of Titans member Starfire. She is portrayed as chaotic, warmongering, spiteful, shady, tricky, cutthroat, very manipulative, and extremely cruel, ruthless, dangerous, immoral, and conniving along with forever having a need to one-up her little sister. Similar to Starfire's attire, Blackfire dresses in a metallic suit with black top, skirt & knee-high boots.
Blackfire first appeared when she arrived on Earth in the Season 1 episode, "Sisters". She gave Starfire a jewel and pretended to enjoy being reunited with her. Blackfire won the Teen Titans' support by having fun with them and telling them stories of adventures she had throughout her travels in the galaxy. The Titans seemed to like her so much, Starfire was beginning to think they wouldn't need her around anymore. She was especially unhappy with her sister's attempts at flirting with Robin. When Starfire thought of leaving Earth, the Centauri Police showed up and captured her. The Titans rescued her and explained to the Centaurians that they have captured the wrong Tamaranean. The Titans then discovered that Blackfire had framed Starfire for crimes by giving her a stolen jewel from the Centauri System. Blackfire, who was leaving Earth at that exact moment, was defeated by her younger sister Starfire and taken to prison, swearing revenge on her sister.
Blackfire later broke out from prison and wrested control of Tamaran as its new Grand Ruler in the Season 3 episode, "Betrothed". Blackfire attempted to get revenge on Starfire by forcing her to marry Glgrdsklechhh, a member of an alien race supposedly set to attack Tamaran. However, this was actually part of an elaborate plot between Blackfire and Glgrdsklechhh; by marrying Starfire to Glgrdsklechhh, he would reward Blackfire with a very powerful jewel. When her ruse was uncovered, Blackfire was once again defeated by Starfire and banished from Tamaran.
- Starfire: "Sister, that nebula is full of black holes. You know travel there is forbidden." Blackfire: "Most fun things in life are."
- “Well after you had me thrown in jail, I got bored. So I broke out and took over Tamaran for kicks.”
- "That's right. Bow down before your Grand Ruler."- to Starfire (Betrothed)
- "Sister Dear"-Blackfire's condescending name for Starfire, ending almost every sentence spoken to her
- In addition to voicing both Blackfire & Starfire in "Teen Titans", Hynden Walch also voiced the two, as well as Madame Rouge in the later series "Teen Titans Go!".