Green’s Dictionary of Slang

creeper n.

[fig. uses of SE, they all creep around]

1. [17C+] a toady, a sycophant.

2. [17C+] a louse.

3. [early 19C] a penny-a-line hack journalist.

4. [20C+] (Und./police) a sneak-thief, esp. when also a prostitute or her accomplice.

5. [1910s+] (orig. US black) an adulterous or cheating lover.

6. [1940s–50s] (US black) a police officer.

7. [1990s+] a burglary committed when the owners are at home.

8. see creep joint n. (3)

In compounds

creeper joint (n.) [joint n. (3a)]

[1930s] (US) an opium den where the semi-conscious sleepers are robbed of their possessions.