Diego Costa Bastos Walsh (born 8 December 1979) is a Brazilian footballer who last played for TOT S.C. in the Thai Premier League.

While growing up in Brazil, Diego played in the youth system of Santos FC, before moving to Miami, Florida at the age of 14.

After a brief stint with Real Salt Lake in the 2006 pre-season, he was released again, and played for Miami FC along with Brazilian superstar Romario where the pair helped the team make it to the USL playoffs in its first year in the league.

Adelaide coach Aurelio Vidmar cited Diego's 19 starts out of a possible 41 in two seasons, as a key factor in the decision.

"He missed 50 per cent of the games due to injury – hamstrings, quads and back," said Vidmar.