Ass-kisser and Yes-man

Ass-kisser noun - A person who tries to please someone in order to gain a personal advantage.

Yes-man and ass-kisser are semantically related in sycophant topic. In some cases you can use "Yes-man" instead a noun phrase "Ass-kisser".

Yes-man noun - A person of unquestioning obedience.

Ass-kisser and yes-man are semantically related (North American) in sycophant topic. You can use "Ass-kisser" instead a noun phrase "Yes-man", if it concerns topics such as brown-nose, someone following orders without question, vulgar slang.