Television characters introduced in 2001

Paige Matthews is a fictional character from the American television series Charmed, played by Rose McGowan from October 4, 2001 until May 21, 2006. The character was created by executive producer Brad Kern as a replacement for lead character Prue Halliwell, following the departure of actress Shannen Doherty. Paige is introduced in season four as the fiercely independent younger half-sister of the show's remaining female leads, sisters Piper (Holly Marie Combs) and Phoebe Halliwell (Alyssa Milano). Like her sisters, Paige is a witch, and more specifically, one of the "Charmed Ones"—three of the most powerful witches of all time. Paige is introduced as the secret love child of the Halliwell sisters' mother Patty (Finola Hughes) and her "whitelighter" (guardian angel) Sam Wilder (Scott Jaeck), making Paige both a witch and whitelighter. She was given up at birth and raised by her adoptive parents.

Elliot Reid, M.D. is a fictional character played by Sarah Chalke in the American comedy-drama Scrubs. She has appeared in every episode during the first eight seasons except two Season 8 episodes, "My Last Words" and "My Lawyer's in Love".

Jack Bauer is the main protagonist of the American television series 24. His character has worked in various capacities on the show, often as a member of the fictional Counter Terrorist Unit (CTU) based in Los Angeles, and working with the FBI in Washington, D.C. during season 7. Within the 24 storyline, Bauer is a key member of CTU and is often portrayed as their most capable agent. Bauer's job usually involves helping prevent major terrorist attacks on the United States, saving both civilian lives and government administrations. On many occasions Jack does so at great personal expense, as those he thwarts subsequently target him and his loved ones. Bauer's frequent use of torture to gather information has generated much controversy and discussion. Entertainment Weekly named Jack Bauer one of The 20 All Time Coolest Heroes in Pop Culture.

Carla Espinosa, RN is a fictional character in the American comedy-drama Scrubs, portrayed by Judy Reyes.

Sydney Anne Bristow (played by Jennifer Garner) is a fictional character and the protagonist of the television series Alias. She is an American woman with a Russian-Canadian family background who works as a spy for the CIA.

Chloe Sullivan is a fictional character in the television series Smallville, which is based on the Superman and Superboy comics published by DC Comics. Portrayed by series regular Allison Mack, the character was created exclusively for Smallville by series developers Alfred Gough and Miles Millar. Other than main character Clark Kent, Chloe is the only main character to last the duration of the show, though Mack only signed on for five episodes in the tenth and final season. The character has also appeared in various literature based on Smallville, an internet series, and was then later adapted back into the original Superman comics which inspired Smallville.

Invader Zim is an American animated science fiction dark comedy television series created by comic book writer and cartoonist Jhonen Vasquez for Nickelodeon. The series centers on an extraterrestrial named Zim (voiced by Richard Steven Horvitz), from the planet Irk, and his mission to conquer Earth and enslave the human race along with his malfunctioning robot servant GIR (Rosearik Rikki Simons). He is antagonized by Dib (Andy Berman), a young paranormal investigator who is determined to stop Zim from succeeding.

Rita Ortiz was a character in the long running police drama series NYPD Blue. She was played by Jacqueline Obradors.

Clark Kent is a fictional character on the television series Smallville. The character of Clark Kent, first created for comic books by Jerry Siegel and Joe Shuster in 1938 as the alternate identity of Superman, was adapted to television in 2001 by Alfred Gough and Miles Millar—this is the fourth time the character has been adapted to a live-action television series. Clark Kent has been played continually by Tom Welling, with various other actors portraying Clark as a child. The character has also appeared in various literature based on the Smallville television series, none of which directly continues from or into the television episodes. As of 2011, Smallville's Clark Kent has appeared in eighteen young adult novels.

Heather Kessler, also known as Lady Heather, is a fictional character on the CBS crime drama CSI: Crime Scene Investigation, portrayed by Melinda Clarke.