GromBeestje

The OAuth plugin for WordPress allows you to provide authentication against any 
OAuth provider. This plugin is uses the OAuth library by Manuel Lemos. The 
plugin allows the admin to select any from the services supported 
out-of-the-box by the said library. Additionally it is possible to configure a 
service manually, which means any site supporting the OAuth protocol can 
be used.

BlaatLogin: OAuth

This plugin turns your WordPress website into an OAuth Consumer. It allowsallows your users to sign in with any OAuth provider.

hillstone

This plugin provides single sign-on capabilities for Hillstone web sites using Hillstone user center authentication(OAuth 2.0).

Hillstone WP SSO

Allows users to login by authenticating with Hillstone user center account via OAuth 2.0.

BlaatLogin: OAuth vs Hillstone WP SSO