walk-on 
(wôkŏn′, -ôn′)
(wôkŏn′, -ôn′)n.
1.
a. A minor acting role, as in a play or on a television episode, usually without speaking lines.
b. A performer playing such a role.
2. Sports A collegiate athlete who has not been recruited and has no athletic scholarship.
walk-on′ adj.