  "Changing-look" active galactic nuclei (CL-AGNs) challenge our basic ideas
about the physics of accretion flows and circumnuclear gas around supermassive
black holes. Using first-year Sloan Digital Sky Survey V (SDSS-V) repeated
spectroscopy of nearly 29,000 previously known AGNs, combined with dedicated
follow-up spectroscopy, and publicly available optical light curves, we have
identified 116 CL-AGNs where (at least) one broad emission line has essentially
(dis-)appeared, as well as 88 other extremely variable systems. Our CL-AGN
sample, with 107 newly identified cases, is the largest reported to date, and
includes $\sim0.4\%$ of the AGNs reobserved in first-year SDSS-V operations.
Among our CL-AGNs, 67% exhibit dimming while 33% exhibit brightening. Our
sample probes extreme AGN spectral variability on months to decades timescales,
including some cases of recurring transitions on surprisingly short timescales
($\lesssim 2$ months in the rest frame). We find that CL events are
preferentially found in lower-Eddington-ratio ($f_{Edd}$) systems: Our CL-AGNs
have a $f_{Edd}$ distribution that significantly differs from that of a
carefully constructed, redshift- and luminosity-matched control sample
(Anderson-Darling test yielding $p_{\rm AD}\approx 6\times10^{-5}$; median
$f_{Edd}\approx0.025$ vs. $0.043$). This preference for low $f_{Edd}$
strengthens previous findings of higher CL-AGN incidence at lower $f_{Edd}$,
found in smaller samples. Finally, we show that the broad MgII emission line in
our CL-AGN sample tends to vary significantly less than the broad H$\beta$
emission line. Our large CL-AGN sample demonstrates the advantages and
challenges in using multi-epoch spectroscopy from large surveys to study
extreme AGN variability and physics.
