I hope you realize Slenderman isn't from Slender.
And that in 2006 a Photoshop contest was made, and someone made photos with a creation they made titled Slenderman. Then he spiraled into popularity, soon becoming a Creepypasta, and Slender was made long after Slenderman was made.
Sorry it just really irritates me when people think Slenderman is from Slender.