Karen Beecher met Mal Duncan when he was in the Teen Titans original team. They worked together on developing the Gabriel Horn, and it was during this project that they fell in love.
Because Karen felt that the Titans did not appreciate Mal, she went back to the drawing board and came up with the Bumblebee's uniform and equipment.
She broke into Titans Lair: a move which led the Titans to believe that she was an enemy.
Her true plan was meant to give Mal a chance to flex his powers and look good in front of the other titans, but Mal's teammates defended him, this ended when Bumblebee escaped, with her identity still intact. Karen learned how much Mal's friends respected and cared for him. Karen revealed her identity to Mal and also to the Titans, and she apologized for her actions. Eventually, Bumblebee joined the Teen Titans, she was a member until the group disbanded.
Karen took night classes in physics, computer technology and political science.
Karen retired from being a super heroine and married Mal Duncan. She received an offer to work at the San Francisco branch of S.T.A.R. Labs as a research technician.
Bumblebee aided the Titans again during the Technis Imperative conflict
She was a member in Titans L.A was formed with that included Beast Boy, Flamebird, Herald, Terra, Hero Cruz, Captain Marvel Jr. and Bushido.
Karen continued to work at S.T.A.R. Labs as an engineer and designer for non-lethal weapons.
She was part of Donna Troy's team of heroes for a space mission during the Infinite Crisis, along with Mal. During their mission, Bumblebee was irradiated with a strange kind of energy which caused her to shrink down to six-inch height. Trapped at this size, the diminutive heroine must take special medication to keep her tiny heart from going into cardiac arrest.
Bumblebee and Vox decided to join the Doom Patrol. There, Karen became confident and friend of Rita Farr. Recently, she's helping her team to fight The Aristocrats.
In the Teen Titans cartoon series, Bumblebee is a member (and possibly the leader) of Titans East, originally seen working undercover as a member of Brother Blood's H.I.V.E. Academy. This version of Bumblebee can shrink down in size while growing wings for flight, and fires electrical blasts from two weapons shaped like the letter "B", giving her similarities to Wasp of Marvel Comic fame. She initially has an antagonistic relationship with Cyborg, but the two later become friends. She makes her second last appearance in Season 5 episode Calling all Titans where she is captured by Punk Rocket and Angel. She then makes another appearance in the next episode, Titans Together alongside Starfire and Red Star, where it appears she has escaped and defeated Angel and Punk Rocket. Along with all the other Teen Titans, she goes into an ultimate showdown with the Brotherhood of Evil, which ends with the Titans winning. Later she is seen at the end of the episode among other Titans waiting to take down a very surprised Dr Light.
We are introduced to Karen Beecher in episode 10 of Young Justice, 'Targets'. She appears to be a popular girl who is part of the cheerleaders who are coincidentally called the Bumblebees. We are made to assume she is dating Mal Duncan since there appearance together but she makes several comments on how attractive she finds Superboy. She was voiced by Masassa Moyo.
Young Justice: Invasion
In the sequel series, set five years after the original, Karen is now an official member of the Team as Bumblebee. She is a student of the Atom, presumably explaining her shrinking abilities. Her relationship with Mal is shown to have grown somewhat strained, as she is uncomfortable when he asks to stay at her apartment after Mount Justice is destroyed.
For years Karen had no special powers. Her abilities came from her super-suit. The suit gives her enhanced strength and she also uses it as a body armor. It also allows her to create powerful sonic blasts. At times she has used other bee-themed gadgets as well (honey entangles, electric stings, U-V vision, etc). As a result of her participation in a mission (see details above) Bumblebee is currently stuck at the size of a little bee.