Reaction Records was an independent British record label, run by music executive Robert Stigwood in 1966 and 1967. Although Reaction released only three albums, one EP and eighteen singles in its brief existence, its roster included two of the most popular British bands of the time, The Who and Cream.

The label's first single, The Who's "Substitute", was released several times with different B-sides due to the band's legal dispute with their former record producer, Shel Talmy. This experience could be seen as one of the deciding factor in the Who's manager's Kit Lambert and Chris Stamp deciding to form their own Track Records label which was also distributed by Polydor Records.

Polydor's involvement with these two labels (as well as Giorgio Gomelsky's Marmalade label) can be seen as a learning process by Polydor who were interested in expanding their base and had little or no experience in the 1960s pop/rock market; at the time, most of their business was done in the easy listening genre, as exemplified by Bert Kaempfert.

Stigwood operated the RSO Records label in the 1970s and 1980s. As with Reaction, RSO was distributed through Polydor Records.