tanka poet
Specifically a poet who composes tanka (31-syllable Japanese poems). Not a general term for all poets.
彼女は現代を代表する歌人として知られている。
She is known as a leading contemporary tanka poet.
祖父は若い頃から歌人として活動していた。
My grandfather had been active as a tanka poet since he was young.
She is widely known as a tanka poet.
He became a tanka poet at a young age.
俳人 is a haiku poet, whereas 歌人 is a tanka poet, so the two terms refer to different poetic forms.
Compound of 歌 (uta, 'song; poem') and 人 (hito, 'person'), referring to a person who composes waka (classical Japanese poetry), especially tanka.