  {\iota} Ori is a well studied massive binary consisting of an O9 III + B1
III/IV star. Due to its high eccentricity (e = 0.764) and short orbital period
(P orb = 29.13376 d), it has been considered to be a good candidate to show
evidence of tidal effects; however, none have previously been identified. Using
photometry from the BRITE-Constellation space photometry mission we have
confirmed the existence of tidal distortions through the presence of a
heartbeat signal at periastron. We combine spectroscopic and light curve
analyses to measure the masses and radii of the components, revealing {\iota}
Ori to be the most massive heartbeat system known to date. In addition, using a
thorough frequency analysis, we also report the unprecedented discovery of
multiple tidally induced oscillations in an O star. The amplitudes of the
pulsations allow us to empirically estimate the tidal circularization rate,
yielding an effective tidal quality factor Q $\approx 4 \times 10^{4}$ .
