Colin McNab (born 3 February 1961) was Scotland's 2nd chess Grandmaster, fulfiling the requirements for the title in 1992 just after Paul Motwani. After achieving his three norms, he strained to get his rating up to the required 2500 level, and is possibly unique among Grandmasters in only achieving a published rating of 2500 some six years after being awarded the title. The FIDE regulations in force at the time stated that an 'intermediate' rating at any stage during an event would suffice, and that ratings between 2498.5 and 2500 would be rounded up, which is indeed what happened in 1992.
McNab was also the Commonwealth Champion in 1992, and won the Scottish Champion in 1983, 1991, 1993 and 1995. His opening repertoire is noted for its seemingly quiet fianchetto systems, and he has written a book on The Fianchetto King's Indian and co-authored the Ultimate Pirc with John Nunn. He is renowned as an expert on the endgame and has written a regular column for Scottish Chess magazine for a number of years. He is also a doctor of mathematics, having studied for a DPhil at Oxford University.