Someone who comes off as a conceited predator.
The term has been thought to predate the '70's as a high school term for a conceited student or self-involved faculty member. It has been shared around the internet in forms of T-shirts with slogans such as 'So pretty but nearly extinct' and has been adapted by cartoon artists and musicians alike including Cat and Girl and Lisa Menzel's Morris & The Narcissaurus.
Would you listen to this windbag? He's so pompous. What a narcissaurus!