Measures regime characteristics (democracy/autocracy) for all states over 500,000 from 1800 to 2018.

Data on alliances, militarization, disputes, and other indicators of conflict since 1816.

Compiles data and microdata on political motivated conflict around the world.

Ranks 144 countries against 23 indicators ranging from military expenditure to respect for human rights.

From the Department of Homeland Security and the University of Maryland, searchable database of over 100,000 terrorism incidents between 1970 and 2011.

Journal of Peace Research replication data plus other datasets such as the Centre for the Study of Civil War data and Small Arms Trade database.

Data on all international transfers of seven categories of major weapons from 1950 to present.

600 peace operations between 2000-2019. Continuously updated. [Most recent version unavailable as of 7/15/2020.]

Datasets on armed conflict between states, government against civilians, peace agreements between parties, and more.

Article from Perspectives on Terrorism listing and describing a number of databases and data sets on the GWOT.

From Tufts Center for Strategic Studies, creating a omprehensive dataset of all US military interventions from 1776 until 2017 to measure the costs, benefits, and unintended consequences of US military involvements abroad.