Eve Teschmacher was a character in Superman: The Movie, and Superman II. She is Lex Luthor's assistant and perhaps girlfriend. She is very sexy, and attractive, and that's why Luthor chose her as his girlfriend. In the film, Ms. Teschmacher acts as a supporting character to both Luthor and Superman. Despite being Luthor's girlfriend, she has feelings for Superman, and she later saves him from drowning after Luthor outsmarts him. She also kisses him,being the only person to do so in the movie.
Superman: Red Son
In the world of Superman: Red Son, Eve Teschmacher made a cameo as Luthor's secretary.
Smallville
Tess Mercer may be a version of Ms. Teschmacher, due to the similar name and her her status as Luthor's second in command. Her character may be merged with that of Mercy Graves.
In season 8, Tess Mercer has taken over Lex's job and place in the mansion. She is also the new editor of the Daily Planet.