ColourPop Dr. M is a slightly warm-toned, dark teal with a matte finish. It is a permanent lipstick that retails for $6.50 and contains 0.11 oz.
ColourPop Dr. M Ultra Matte Liquid Lipstick ($6.00 for 0.11 fl. oz.) is described as a "deep blackened green." It's a cool-toned, green-leaning teal with very, very subtle emerald green pearl. It's such a cool color, and I love that it applied with fully opaque, even color, but it emphasizes the texture/lines of the natural lip tremendously in a way that makes them appear raisin-like. Despite this, it didn't seem to "crack" when I smiled, but it was a little more uncomfortable to wear (I felt more aware of it on than other shades in the range, even for liquid lipstick). It wore for nine hours and was moderately drying after five hours of wear.
Illamasqua Apocalips (P, $24.00) is less shimmery, lighter, cooler (80% similar). Anastasia Insomniac (P, $20.00) is lighter, cooler (85% similar). Makeup Geek Twerk (LE, $12.00) is darker, more muted (85% similar). Anastasia Requiem (P, $20.00) is more shimmery, darker, more muted (80% similar). MAC Young Attitude (P, $21.00) is darker, cooler (80% similar). Obsessive Compulsive Cosmetics Chlorophyll (DC, $18.00) is lighter, warmer, glossier (80% similar). MAC Show and Teal (LE, $20.00) is lighter, cooler (80% similar). Fenty Beauty Turks and Caicos (P, $18.00) is less shimmery, lighter, cooler (80% similar). Ciate Siren (P, $19.00) is more shimmery, cooler (80% similar). See comparison swatches / view dupes side-by-side.
FURTHER READING: Formula Overview, which is a detailed review of the range as a whole.