'(Kreacher) did not wish to tell me ...But I am a sufficiently accomplished Legilimens myself to know when I am being lied to and I - persuaded him - to tell me the full story."
-- Albus Dumbledore (OP37)
"My Lord! I -- I have no wish to leave you, none at all --"
"Do not lie to me! ...I can always tell, Wormtail! You are regretting that you ever returned to me. I revolt you..."
-- Peter Pettigrew and Lord Voldemort (GF1)
"I know he believes you, but. . ."
"You think he is mistaken? Or that I have somehow hoodwinked him? Fooled the Dark Lord, the greatest wizard, the most accomplished Legilimens the world has ever seen?"
-- Bellatrix Lestrange and Severus Snape, who actually did hoodwink the Dark Lord (HBP1)
Someone who practices Legilimency to extract thoughts and emotions from another’s mind is called a Legilimens (OP37).
- Severus Snape is both a Legilimens and an Occlumens, and is apparently better at Occlumency than Voldemort is at Legilimency, which is how he has survived in his difficult role of double agent among the Death Eaters for so long.
- Voldemort is a highly skilled Legilimens, in the estimation of Severus Snape (OP24), to the point where Voldemort can nearly always tell when someone is lying to him.
- Dumbledore is also a Legilimens, describing himself as sufficiently skilled to know when he is being lied to. He is also sufficiently skilled in Occlumency to be able to teach it if he so wishes (OP37).
- Bellatrix Lestrange was able to teach Draco Occlumency, so we can assume she is also a Legilimens (HBP15).