The James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-domain Field (TDF) is a >14' diameter field optimized for multiwavelength time-domain science with JWST. It has been observed across the electromagnetic spectrum both from the ground and from space, including with the Hubble Space Telescope (HST). As part of HST observations over three cycles (the "TREASUREHUNT" program), deep images were obtained with the Wide Field Camera on the Advanced Camera for Surveys in F435W and F606W that cover almost the entire JWST NEP TDF. Many of the individual pointings of these programs partially overlap, allowing an initial assessment of the potential of this field for time-domain science with HST and JWST. The cumulative area of overlapping pointings is ~88arcmin^2^, with time intervals between individual epochs that range between 1 day and 4+ yr. To a depth of m_AB_~29.5mag (F606W), we present the discovery of 12 transients and 190 variable candidates. For the variable candidates, we demonstrate that Gaussian statistics are applicable and estimate that ~80 are false positives. The majority of the transients will be supernovae, although at least two are likely quasars. Most variable candidates are active galactic nuclei (AGNs), where we find 0.42% of the general z<~6 field galaxy population to vary at the ~3{sigma} level. Based on a 5yr time frame, this translates into a random supernova areal density of up to ~0.07 transients arcmin^-2^ (~245deg^-2^) per epoch and a variable AGN areal density of ~1.25 variables arcmin^-2^ (~4500deg^-2^) to these depths.

Cone search capability for table J/ApJS/272/19/table2 (Transients identified in HST TREASUREHUNT observations of the James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-domain Field (TDF); see Section 4.1)

Cone search capability for table J/ApJS/272/19/table5 (Variable sources identified in HST TREASUREHUNT observations of the JWST NEP TDF; see Section 4.2)