From the Super Mario Wiki
Not to be confused with Lina
“Everyone deserves what they've earned! And I've earned this!”
—Lena, Super Mario Bros.
Lena is President Koopa's assistant in the Super Mario Bros. film. She appears to be President Koopa's lover.
In the beginning of the movie, Lena seems to be enjoying the high life with Koopa. However, when he finds Princess Daisy, she becomes exceedingly jealous and feels that everything that she's worked for, to be by Koopa's side and rule the world with him, have been dashed to pieces. After she finds the piece of meteorite needed to merge the two worlds, she comes back to him, but he spurns her. Lena then decides to take matters into her own hands and attempts to merge the two worlds on her own. Koopa figures this out, and arrests her. Later, however, during Koopa's fight with Mario, he drops the meteorite and she grabs it again. She finds the meteor and tries to put the piece back in. Her plans prove deadly, and as she puts the meteor piece back in the with larger meteor, she is electrocuted and immediately reduced to a skeleton that gets stuck to the rock wall.
While gloating about how she had succeeded in acquiring the meteorite, she states that "the universe is hers," which implies that she most likely wanted to use the meteor rule the entire universe, without any regard to her people.
Lena was played by Fiona Shaw of Harry Potter fame.