Cinderblock is a villain that first appeared in the first episode of Teen Titans (2003). He later made his comics debut in Titans #17 (November 2009).
Although Gizmo had already appeared in comics prior to the Teen Titans episode "Final Exam" (2003), he appeared in the show in a greatly altered form. This form was brought back into comics as Gizmo II, the original Gizmo's son, in DC Special: Cyborg #5 (November 2008).
Red X first appeared as an undercover identity for Robin in the Teen Titans episode "Masks" (2003), and later, in the episode "X" (2004), somebody steals the costume and begins using the persona for himself. In Terror Titans #2 (January 2009), Red X is mentioned as a thief the team is looking for.
Billy Numerous first appeared on Teen Titans as a background character in the season 3 premiere, "Deception" (August 2004); his first full appearance was season 4's "Overdrive"(June 2005). He first appeared in comics in Catwoman #79 (July 2008).
(Note: internet consensus is that the character that appeared in Catwoman is Billy Numerous, but he could just as easily be The Batman's Everywhere Man, or a combination of both.)
Mas y Menos
Mas y Menos first appeared in the Teen Titans cartoon, beginning with the episode "Titans East, Part 1" (2005); they later had a cameo appearance in Teen Titans #38 (September 2006).
Teen Titans also affected the looks of several characters and introduced some other ideas as well:
Left: Beast Boy's original look
Middle: Beast Boy's look on Teen Titans
Right: Beast Boy's One Year Later look, beginning with Teen Titans #34 (April 2006)
Middle: Cyborg on Teen Titans
Right: Cyborg 2.0, from the Titans Tomorrow storyline (December 2004)
Hot Spot's name and look
Middle: His look in Teen Titans
Right: His current look
Originally using the name Joto (Swahili for "heat"), he was called "Hot Spot" when he appeared on the Teen Titans cartoon - presumably because it's more easily associated with his powers (and, according to Rorshach_42 on the CBR forums, "Joto" is a slur in Spanish). When he joined the Teen Titans during the One Year Gap (Teen Titans #34, April 2006), he also used the name.
Left: Bumblebee's original look
Middle: Bumblebee on Teen Titans
Right: Bumblebee as she appeared One Year Later, starting with Teen Titans #34 (April 2006)
The HIVE Academy first appeared in the Teen Titans episode "Final Exam" (2003) as a training ground for supervillains. In DC Special: Cyborg #6 (December 2008), Gizmo II was mentioned to have formerly been a student there.
Teen Titans' Hometown
Despite the Titans' usually being based out of New York City, the animated series (July 2003) put them in an unnamed city on the West Coast that felt a lot like San Francisco. In Teen Titans #1 (September 2003), the team moved to San Francisco proper.