RGs, although there appear to be some cases of disk dominated host galaxies (McHardy 1991; Abraham 1991; Stocke, Wurtz & Perlman 1995, but see contradicting views by Romanishin 1992; Stickel 1993; Falomo 1997a). The extended radio power and optical environments of BL Lacs are also consistent with those of F–R I RGs, but suggest a contribution to the parent population from F–R II RGs (Kollgaard 1992; Pesce, Falomo & Treves 1995; Wurtz 1997).

Very little near–infrared (NIR) imaging exists on BL Lac objects. However, NIR wavelengths may offer some advantages. Optical emission from BL Lacs is often dominated by the nuclear source, while the luminosity of the massive old stellar population peaks in the NIR. This leads to a better contrast of the nebulosity with respect to the nuclear source at these wavelengths. One also needs to apply much lower K–correction in the NIR than in the optical. In this paper we present NIR H–band (1.65 $\mu$m) images of 11 BL Lac objects and compare the NIR host properties with those of RGs and FSRQs. The BL Lacs were observed during our project to study the host galaxies of a complete sample of FSRQs (Kotilainen, Falomo & Scarpa 1998; hereafter 