New Limits on Doubly Charged Bileptons from CERN LEP Data and the Search at Future Electron-Positron and Electron-Photon Colliders

We show that the accumulated LEP-II data taken at $sqrt{s} =$ 130 to 206 GeV can establish more restrictive bounds on doubly charged bileptons couplings and masses than any other experiment so far. We also analyze the discovery potential of a prospective linear collider operating in both $e^+ e^-$ and $e gamma$ modes.