Sebastian Patrick Quintus Rahtz (13 February 1955-15 March 2016) was Chief Data Architect for the University of Oxford and a member of Wolfson College and its Digital Research Cluster. This series of short talks by colleagues celebrates 'SPQR' and his many and varied achievements in Humanities computing. Sebastian’s involvement with free and open source software goes back to the late 1980’s as a developer in the community around the TeX typesetting system on which he published widely. He maintained an open source TeX distribution for ten years and a variety of TeX-related packages. He was an active member of the XML and XSLT communities most importantly as one of the technical leads for the Text Encoding Initiative in which he served on the Board of Directors and Technical Council over many years. He was also Director of Academic IT Services and setup the JISC-funded national advisory service for open source software, OSS Watch, and worked on linked data projects such as CLAROS.