Shield Security - The most advanced and easy-to-use WordPress security plugin.
Sucuri - Website Protection, Malware Removal, and Blacklist Prevention
Defender - Encompassing security solution for WordPress.
WP Hacked Help - WP hacked help is a popular online Wordpress malware removal service.
Imperva Cloud Application Security - Deploy your applications and data where you want. When you want. Imperva keeps them secure in the cloud, on premises, and in hybrid clouds.
WP Hide & Security Enhancer - Similar name but is a different program. Protects Wordpress sites by changing or hiding addresses of common points of attack - can also be used to deactivate unused functions and hide that the site is run by Wordpress. More info www.wp-hide.com.