In Tennis it is called 'appearance fee'
'Federer also pads his bank account as the top draw for exhibition matches. He commands appearance fees of at least $2 million for certain exhibitions because he can move the needle on ticket sales. Federer pulled in $60 million from sponsors and appearance fees by Forbes’ count, along with $7.8 million in prize money.'
http://www.forbes.com/sites/kurtbadenhausen/2016/08/30/feder...'To attract top players in order to sell sponsorships and tickets, tournaments often pay appearance fees to top players, which can escalate expenses by as much as 25 percent.'
http://www.tennisindustrymag.com/articles/2010/09/profession...