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Extreme (band), an American band, most well-known for its ballad "More than Words"

Extreme weather, severe or unseasonal weather

Extreme value, the largest and the smallest element of a set

Extremism, ideas or actions beyond what is deemed acceptable

Extreme sport, featuring speed, height, danger or spectacular stunts

Extremophile, an organism which thrives in or requires "extreme" conditions

Extreme Associates, a pornographic video and DVD company

Extreme Programming, also known as XP

Extreme (marketing), the term as used in advertising and marketing

Dance Dance Revolution EXTREME

Extreme Championship Wrestling, the former independent promotion that now operates as a brand for World Wrestling Entertainment.

Extreme Paintbrawl, a budget first person shooter that is considered one of the worst games ever

Extreme, an autobiography by Sharon Osbourne

Extreme Networks, a California based enterprise level networking hardware company

Adam X the X-Treme, a Marvel Comics character also known as Adam X or Adam Neramani

Agostino Carollo, an Italian singer, disc jockey, and producer, better known as "X-Treme"

Xtreme Pro Wrestling