Spike
This character was created after the civil rights movement due to the negative response of critics noticing that every character in the comic strip was white.
Franklin
This character, with an ironic name (unknown if its his actual name or nickname) appeared in the late 80s, 90s, and in 2000 as the younger brother of Linus.
Rerun
This character was one of the three original characters from the 1950s with Charlie Brown and Patty. He was a major character from about the 50s to 60s and slowly faded into inexistence into the 70s and 80s, never to be seen again and forgotten about.
Shermy.
This character, despite appearing in media such as short films in the 90s and 2000s, barely appears in the comic strip at all. He is Charlie Brown's temporary friend when he heads to camp, and he is a little unusual and annoying.
Roy