https://en.m.wikipedia.org/wiki/Roundarm_bowling
In the modern game, the Sri Lankan pace bowler
Lasith Malinga has a very distinctive action which is authentic roundarm.
[2]This has earned him the name "Slinga Malinga". There are some who question the legality of this action, but it is legal, because his arm does not straighten from a bent position as he bowls. This is the strict definition of bowling vis-à-vis throwing. In fact, many bowlers bowl with a slightly bent arm; the key is that they do not straighten it as they bowl.