Simon Tatham (born 3 May 1977) is a British computer programmer. He created and maintains PuTTY, a free software implementation of Telnet and Secure Shell (SSH) clients for Unix and Windows API platforms, along with an xterm terminal emulator. He is also the original author of Netwide Assembler (NASM), and maintains a collection of small computer programs which implement one-player puzzle games. All of them run natively on Nintendo DS, Symbian S60, Unix (GTK+; Android, MacOS), and Windows.
Many software developers direct users to read his essay, "How to Report Bugs Effectively", before reporting bugs to them.
He attended University of Cambridge, and currently works at ARM Holdings.