  We present XMM-Newton observations of Mrk 359, the first Narrow Line Seyfert
1 galaxy discovered. Even among NLS1s, Mrk 359 is an extreme case with
extraordinarily narrow optical emission lines. The XMM-Newton data show that
Mrk 359 has a significant soft X-ray excess which displays only weak absorption
and emission features. The (2-10) keV continuum, including reflection, is
flatter than the typical NLS1, with Gamma approximately 1.84. A strong emission
line of equivalent width approximately 200 eV is also observed, centred near
6.4 keV. We fit this emission with two line components of approximately equal
strength: a broad iron-line from an accretion disc and a narrow, unresolved
core. The unresolved line core has an equivalent width of approximately 120 eV
and is consistent with fluorescence from neutral iron in distant reprocessing
gas, possibly in the form of a `molecular torus'. Comparison of the narrow-line
strengths in Mrk 359 and other low-moderate luminosity Seyfert 1 galaxies with
those in QSOs suggests that the solid angle subtended by the distant
reprocessing gas decreases with increasing AGN luminosity.
