  We discuss the recent detection of a strong, organized magnetic field in the
bright, broad-line B2V star, HR 5907, using the ESPaDOnS spectropolarimeter on
the CFHT as part of the Magnetism in Massive Stars (MiMeS) survey. We find a
rotational period of 0.50833 days, making it the fastest-rotating,
non-degenerate magnetic star ever detected. Like the previous rapid-rotation
record holder HR 7355 (also discovered by MiMeS: Oksala et al. 2010, Rivinius
et al. 2010), this star shows emission line variability that is diagnostic of a
structured magnetosphere.
