Cog Effects is a builder of hand-made guitar and bass effects pedals based in Sheffield, South Yorkshire, UK. Founded in 2013 by Tom George, the company operates as a small independent workshop, producing both a stock line of pedals and fully custom builds tailored to individual players' rigs. Every unit is assembled in Sheffield using through-hole components and in-house printed circuit boards.

The brand is particularly well-known among bassists, though its catalog covers guitar as well. Notable products include the Tarkin and Grand Tarkin fuzz pedals (with the Grand Tarkin voiced specifically for bass), the Knightfall 66 overdrive and its Mini 66 counterpart, and the T-series of analog octave pedals — the T-16, T-47, T-65 and T-70 — each offering different combinations of sub-octave, upper-octave and dry-signal voicings. Cog also offers pedalboard wiring and custom enclosure work.

In addition to its stock range, Cog Effects has built one-off and custom pedals for touring musicians, and its output is regularly discussed in bass-focused communities such as TalkBass. The company's reputation rests on bespoke, low-volume production rather than mass-market distribution.

Cog Effects has 9 products cataloged on Equipboard, including Fuzz Effects Pedals, Switch Effects Pedals, and Harmonizer & Octave Effects Pedals. Their gear is featured by 2 artists, with the strongest followings in Rock. Notable users include Mike Kerr and Tim Commerford.