Former Lions James Hook, Matthew Rees and Dwayne Peel have been named in a 22-man party, which also included Paul James and Duncan Jones.
Players from ten different nationalities have been named in the squad, which has been selected by head coach Dai Young and manager Derek Quinnell.
Ospreys scrum half Kahn Fotuali’i, former All Blacks Nick Evans and Joe Rocokoco and and USA wing Takudzwa Ngwenya are among the stars.
The Barbarians play England at Twickenham on May 26, before jetting to Hong Kong to face Warren Gatland’s Lions six days later.
“Our selection process has taken several months and is still not quite complete,” said Barbarians team manager Quinnell.
“Over the next week or so we will be monitoring the domestic play-off matches in Europe and the various national squads for the summer tours.
“Also, one or two players in the squad announced today may not be available for both of our matches, so we expect to add other significant names in the near future.”
Squad: Backs – J Payne (Ulster), R Varty (DeA Tigers and Hong Kong), T Ngwenya (Biarritz and USA), J Rokocoko (Bayonne and New Zealand), J Hook (Perpignan and Wales), N Evans (Harlequins and New Zealand), K Fotuali’I (Ospreys and Samoa), D Peel (Sale Sharks and Wales), D Yachvili (Biarritz and France).
Forwards – D Jones (Ospreys and Wales), B J Botha (Munster and South Africa), P James (Bath and Wales), M Castrogiovanni (Leicester and Italy), M Rees (Scarlets and Wales), L Ghiraldini (Treviso and Italy), M Wentzel (Wasps and South Africa), J Hamilton (Gloucester and Scotland), F Louw (Bath and South Africa), S Jones (Wasps), A Zanni (Treviso and Italy), S Parisse (Stade Francais and Italy), I Harinordoquy (Biarritz and France).