Thread on Russian missile defense countermeasures I couldn't find a home for. According to V.C. Belous, Soviet design bureaus began development of balloon decoys and dipole chaff in the early 1960s; projects dubbed "Willow," "Cactus," and "Mole."

(Belous 2002)

It's hard to find which entities were involved, but the Central Research Radiotechnical Institute (CNIRTI) was the only one I found explicitly named. They reportedly developed varieties of chaff, decoys, jammers, and other devices since the 1950s.

(Spassky et al 2004)

Between 1960 and 1970, the Corporation of Research and Development establishments and other entities developed 9 decoy systems, named "List," "Pa'lma," "Ledokol," "Kiparis," "Bereza," "Kashtan," "Magnolia," "Lavr," and "Vyaz."

(Sergeev et al 2004)

Subsequent programs reportedly focused on low-observable warhead coatings, heavy decoys, and miniaturized active jammers. 3 countermeasures have known GRAU designations: 2 endoatmospheric decoys and one unspecified decoy type.

(Arbatov and Dvorkin 2016, @dnkornev)

@russianforces also mentioned that the USSR developed a few penetration aid sets for the UR-100 ICBM, weighing 176 to 436 kg depending on configuration.

...And that's about all I could find. Here's a final overview from Solomonov (prominent solid-fueled missile designer responsible for Topol-M, Yars, Bulava) on the matter, and my poorly-translated version of the table.

"Cosmosols" apparently refer to aerosol obscurants which are released in space. Supposedly intended to block SDI lasers.