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OB stars powering stellar bowshock nebulae (SBNe) have been presumed to havelarge peculiar velocities. We measured peculiar velocities of SBN central starsto assess their kinematics relative to the general O star population using$Gaia$ EDR3 data for 267 SBN central stars and a sample of 455 Galactic O starsto derive projected velocities $v_{\rm 2D}$. For a subset of each sample weobtained new optical spectroscopy to measure radial velocities and identifymultiple-star systems. We find a minimum multiplicity fraction of 36$\pm$6%among SBN central stars, consistent with $>$28% among runaway Galactic O stars.The large multiplicity fraction among runaways implicates very efficientdynamical ejection rather than binary-supernova origins. The median $v_{\rm2D}$ of SBN central stars is $v_{\rm 2D}$=14.6 km s$^{-1}$, larger than themedian $v_{\rm 2D}$=11.4 km s$^{-1}$ for non-bowshock O stars. Central stars ofSBNe have a runaway ($v_{\rm 2D}$$>$25 km s$^{-1}$) fraction of24$^{+9}_{-7}$%, consistent with the 22$^{+3}_{-3}$% for control-sample Ostars. Most (76%) of SBNe central stars are not runaways. Our analysis ofalignment ($\Delta_{\rm PA}$) between the nebular morphological and $v_{\rm2D}$ kinematic position angles reveals two populations: a highly aligned($\sigma_{PA}$=25$^\circ$) population that includes stars with the largest$v_{\rm 2D}$ (31% of the sample) and a random (non-aligned) population (69% ofthe sample). SBNe that lie within or near HII regions comprise a largerfraction of this latter component than SBNe in isolated environments,implicating localized ISM flows as a factor shaping their orientations andmorphologies. We outline a new conceptual approach to computing the Solar LSRmotion, yielding [U$_\odot$, V$_\odot$, W$_\odot$]= [5.5, 7.5, 4.5] kms$^{-1}$.

Kinematics of the Central Stars Powering Bowshock Nebulae and the Large Multiplicity Fraction of Runaway OB Stars