Wallace (Wally) Spencer Pitcher FGS (3 March 1919 – 4 September 2004) was a British geologist.
Professor Herbert Harold Read of Imperial College offered him a post as a Demonstrator with the opportunity to study granite rocks in Donegal, and Pitcher, with his wife Stella Scutt, started in 1948 a 25-year programme of rock mapping in Donegal.
He developed new procedures based on colorimetry and flame-photometry which speeded up the rock analyses.
In 1972 he published The Geology of Donegal: A Study of Granite Emplacement and Unroofing.
Whilst at Liverpool he took part in field surveys of the rocks in the Peruvian Andes.