Several Code of Conducts are widely re-used by other groups. Some, like Contributor Covenant, were specifically written to be a reuseable CoC for FOSS projects; others like Debian CoC were written for their own projects, but achieved a widespread popularity. Since these are all meant for open source projects, check the license when you use one.
The Code of Conduct in Open Source Projects 2017 paper studied which CoCs were reused the most often (they’re all included below); there are new research tools on GitHub today to try to detect the style of CoC in various repositories.
A very widely-copied CoC written purposefully for reuse by all projects; currently in version 1.4.1.
Written by the TODO Group, a consortia of technology companies, this is declared outdated but is still used by some projects.
A short and high-level CoC that emphasizes positive behaviors: Open, Considerate, Respectful.
A detailed CoC including events, derived from both the Django CoC and the Geek Feminism one.
A highly community-led focused CoC with detailed expectations of positive behaviors.
A medium-length CoC built on the SpeakUp! CoC with a moderate level of detail.
A purposeful CoC for prioritizing diversity, with various guides and reviews of CoCs as well.