Post a character turning completely red in the eyes/going red-eyed

Akaya Kirihara will goes into Bloodshot Mode when he is under high pressure, injured, ou pushed to the point of anger in a match. The whites of his eyes turn red, and his power, skill, and speed increase in this mode... (Prince of Tennis)

Ryner luth from The Legend of Legendary Heroes. When his Alpha Stigma goes out of control, his eyes go red.

Itachi's (Naruto/Naruto Shippuden) eyes become red when he activates his sharingan.

Saya from Blood+ has red eyes, they glow when she uses her power.

Ayato Naoi from Angel Beats when he's hypnotizing someone.

Madara Uchiha (Naruto Shippuden)

Zero <33

zero from vampire knight he is hot with his red eyes

kurapika hunter hunter

Gutoku from Qualidea Code once he mutates had his right eye turn red with black sclera.