Key extra-galactic sources of VHE gamma rays include blazars, gamma-ray bursts (GRBs), and
other interesting transients phenomena. The studies on these targets provides critical insights
into astrophysical phenomena, including black hole accretion, particle acceleration, and explosion
dynamics. The Large High Altitude Air Shower Observatory (LHAASO), located in China, is a
multi-purpose facility designed to detect cosmic rays and gamma rays in the energy range from
a few hundred GeV to a few hundred PeV. As one of three sub-arrays comprising LHAASO, the
Water Cherenkov Detector Array (WCDA), with its wide field of view, high duty cycle, and high
sensitivity, provides an ideal platform for capturing these flaring phenomena, contributing to a
deeper understanding of such astrophysical phenomena. In this talk, we will review the extra-
galactic sources detected by LHAASO-WCDA, along with a preliminary catalog of these sources.
Additionally, we will discuss transient event analysis, including the monitoring framework, anal-
ysis pipeline, and preliminary results.

