An imperfect duplicate of Mr. Mxyzptlk.
In July 1961, Bizarro Junior is experimenting with a duplicator ray and focuses it on Mr. Mxyzptlk, who is flying near Htrae at the time. Thus, he creates an imperfect clone of Mxyzptlk. Like Mxyzptlk, Bizarro-Mr. Kltpzyxm is a "pest," but it is because he has good intentions. By using his magic to do good deeds and improve the planet, he violates the Bizarro Code and is put in prison (Adv No. 286/2: "Bizarro, Private Detective"). His kindheartedness continues to wreak havoc afterwards, when he grants superpowers to Bizarro-Lois (Adv No. 288/2, Sep 1961: "Bizarro's Secret Identity"), and tries to arrange a friendly meeting between Krypto and Bizarro-Krypto (Adv No. 294/2, Mar 1962: "The Halloween Pranks of the Bizarro Supermen").
Unlike Mr. Mxyzptlk, who disappears into the 5th dimension if he says his name backwards, Bizarro-Mr. Kltpzyxm must be tricked into saying his name forwards. Being a Bizarro, he is also vulnerable to Blue Kryptonite.