Courtney Walsh in Tests & Wasim Akram in ODIs.
Courtney Walsh. Shane Warne was 2nd.
Richard Hadlee of New Zeland was the first bowler to take 400 wickets in test matches. Richard Hadlee took his 400th wicket against India on 4th February, 1990 against India at Christchurch.
Dennis Lillee of Australia was the first bowler to take 350 wickets in Test Cricket. He achieved this mark in 1984 in the last match of his Test Cricket career at Sydney playing against Pakistan.
New Zealand's Richard Hadlee became the first bowler to take 400 wickets. His 400th wicket came against India on February 4, 1990, at Christchurch.
who was the first australian to take 400 test wickets