是我见过最

is the most … I’ve ever seen

→ 是
phrase Rare #27,646
is the most … I’ve ever seen The adjective or description comes after 最; the person or thing being described comes before 是.
CH: 她是我见过最勇敢的人。
EN: She is the bravest person I’ve ever met.

她是我见过最漂亮的新娘

She is the most beautiful bride I have ever seen.

— 美国黑帮 (2007)

"是我见过最蠢的白痴"

The stupidest idiot I’ve ever met.

— 汉江怪物 (2006)