  We report the discovery of LXP169, a new high-mass X-ray binary (XRB) in the
LMC. The optical counterpart has been identified and appears to exhibit an
eclipsing light curve. We performed follow-up observations to clarify the
eclipsing nature of the system. Energy spectra and time series were extracted
from two XMM-Newton observations to search for pulsations, characterise the
spectrum, and measure spectral and timing changes. Long-term X-ray variability
was studied using archival ROSAT data. The XMM positions were used to identify
the optical counterpart. We obtained UV to NIR photometry to characterise the
companion, along with its 4000 d long I-band light curve. We observed LXP169
with Swift at two predicted eclipse times. We found a spin period of 168.8 s
that did not change between two XMM observations. The X-ray spectrum, well
characterised by a power law, was harder when the source was brighter. The
X-ray flux of LXP169 is found to be variable by a factor of at least 10. The
counterpart is highly variable on short and long timescales, and its photometry
is that of an early-type star with a NIR excess. This classifies the source as
a BeXRB pulsar. We observed a transit in the UV, thereby confirming that the
companion star itself is eclipsed. We give an ephemeris for the transit of MJD
56203.877 + N*24.329. We propose and discuss the scenario where the matter
captured from the companion's equatorial disc creates an extended region of
high density around the neutron star (NS), which partially eclipses the
companion as the NS transits in front of it. This is most likely the first time
the compact object in an XRB is observed to eclipse its companion star. LXP169
would be the first eclipsing BeXRB, and a wealth of important information might
be gained from additional observations, such as a measure of the possible Be
disc/orbital plane misalignment, or the mass of the NS.
