  Known classes of radio wavelength transients range from the nearby--stellar
flares and radio pulsars--to the distant Universe--\gamma-ray burst afterglows.
Hypothesized classes of radio transients include analogs of known objects,
e.g., extrasolar planets emitting Jovian-like radio bursts and giant-pulse
emitting pulsars in other galaxies, to the exotic, prompt emission from
\gamma-ray bursts, evaporating black holes, and transmitters from other
civilizations. A number of instruments and facilities are either under
construction or in early observational stages and are slated to become
available in the next few years. With a combination of wide fields of view and
wavelength agility, the detection and study of radio transients will improve
immensely.
