Boxers that has the most maintained poker face.

[sunny31]

Ricky Hatton is the best I've seen in the ring.

[Sparked_26]

Audley Harrison

[GhostofDempsey]

Mayweather is the master at this

Not while he was fighting Cotto, Maidana and Ortiz.

I would say Foreman had a good poker face. Holyfield too.

[GMAN SUPREME]

golovkin has one of the best poker faces.

[chirorickyp]

Young Mean George Foreman!!!
Eddie Mustafa Muhammad -- check him out.
Marvin Hagler

[Fanofreason]

Rod Salka!!