As a kid, I am not sure I had a wall .. That was my own, anyway, and never thought about putting up a picture, of someone.
I might have chosen, Bobby Charlton - or someone of that ilk, not even considering cricketers, or, anyone from a different field.
If I had to chose one now, v high on the list, would be Edward O Thorpe.
He has many claims to fame :
PhD maths / physics.
Developed first Blackjack card counting system
Developed first roulette speed measurement device, to create a 44% edge
Developed statistical arbitrage models, for the stock market
Went on to run Hedge funds, that beat the market, (at one of his former companies, for 227 months, losing in only 3)
Was one of the first, to discover Bernie Madorf was a fraud.
He has written quite a few books, or had them written about him, and would commend anyone, to read :
During the days, when he was discoveri mathematical models, for beating blackjack, he also discovered significant edges, in the Baccarat side games.
Specifically, when u can bet, the bank or house, will get dealt a natural 8 or 9.
This paper was released, a long time ago, but, it has just been turned into a book :
It only available in print, so, haven't got a copy yet, but, a decent analysis of the theory, is here :
A true legend
There is a great interview, by Jack D.Schwager , in his book, Hedge Fund Market Wizards, which, I would commend to anyone.