Tactical Studies Rules was formed in 1973 as a partnership between Gary Gygax and Don Kaye as a means to publish formally and sell the rules of Dungeons & Dragons, the first modern role-playing game. The partnership was subsequently joined by Brian Blume and (temporarily) by Dave Arneson.
In 1975 Don Kaye died, the partnership was dissolved and the remaining owners incorporated a new company TSR Hobbies, Inc..
In 1983, the company was split into four companies, TSR, Inc. (primary successor), TSR International, TSR Ventures and TSR Entertainment, Inc..
TSR, Inc. was purchased in 1997 by Wizards of the Coast, and finally, in 1999, this one was also purchased by Hasbro, Inc..
First logo of the company, during 1974-1979, was a symbol made by letters G and K for Gary Gygax and Don Kaye.
was the portion of TSR that published Dragon Magazine and related products, such as Dragontales, calendars, etc. Dragon Publishing was also the US distributor for The Wargamer and White Dwarf.