Cavaliers and Roundheads is a set of rules for English Civil War miniature wargaming.

It was written by Gary Gygax and Jeff Perren and published by Tactical Studies Rules (later TSR, Inc.) in 1973.

[1]: 7  TSR partners Gygax and Don Kaye had originally planned to use the revenue generated by this game to finance the publication of D&D.

[2] The basic troop types are pikemen, heavy infantry, musketeers, cavalry, and lobsters.

Six-sided dice are used exclusively, and melee is resolved like in Chainmail, a ruleset Gygax and Perren also collaborated on.