OU Puppis (OU Pup) is a chemically peculiar class A0 (white main-sequence) star in the constellation Puppis. Its apparent magnitude is about 4.9 and it is approximately 188 light-years away based on parallax.
It is an ñ<sup>2</sup> CVn variable, ranging from 4.93 to 4.86 magnitudes with a period of 0.92 of a day. Its spectrum has unusually strong lines of silicon, chromium, and strontium, making it an Ap star.
Unlike the majority of star pairs, the number attached to the Bayer designation 'L' is generally a subscript: L<sub>1</sub>. Its better-known companion L<sub>2</sub> Puppis is similarly represented.