cubecolour

WordPress 4.5 added the ability to login using the registered user’s email address in place of the username. When this plugin is active, the ability to login using the email address in place of the username is removed, and the label of the input field is changed to reflect this.

No Login by Email Address

Removes the ability to login using the email address instead of the username.

rcdevs

It is versatile, device-independent and based on opened security standards. 
OpenOTP provides fine-grained user identity and access management (IAM), one-time passwords authentication technologies (OTP), Universal Second Factor (U2F) and extensive authentication policies for your AD / LDAP users. 
It is enterprise-ready with strong support for high-availability, load-balancing, multi-tenancy, cloud-readiness, geolocalization, delegated administration and much more.

OpenOTP Two-Factor Authentication

OpenOTP plugin Enable two-factor authentication for your admins and/or users The plugin will transparently handle any OpenOTP Login Mode including, LD …

No Login by Email Address vs OpenOTP Two-Factor Authentication