'The Office' Star Says Racist Attacks Began During BLM Progress, He Won't Ignore

Leslie David Baker -- best known for playing the lovable grouch, Stanley, on "The Office" -- has witnessed the rise of racism along with the surge of the Black Lives Matter movement ... and he's speaking out about it.

The veteran actor joined "TMZ Live" Monday to address how his 'Office' spin-off project led to him becoming the target of hateful attacks, because at the same time ... he's been a vocal supporter of BLM.

Leslie says much like Black athletes being told to "stick to sports," racists began coming out of the woodwork to tell him to "stick to acting" and bombarding him with other vile messages ... and he's had enough.

The actor's urging everyone, including other minorities in entertainment, to call out racism when they encounter it ... because he says ignoring it only protects the bigots and allows the hate to continue.

That's exactly what Leslie's been doing -- he's sharing examples of what he believes is growing racism in this country, to raise awareness and motivate everyone to help put an end to it.