Enlightened Sannyasins - Declared by Osho
Osho talks about few of his enlightened sanyassins
Enlightened Sannyasins - Undeclared
There are others who were enlightened whose names Osho specifically did not mention, so as to not create trouble for them. Ma Yoga Lakshmi comes to mind.
"There are enlightened sannyasins. It is just out of gratitude that they don't want their names to be declared. While I am here, they don't want themselves to be declared as enlightened. I would love to declare them, but I can understand their difficulties. People will start feeling jealous, people will start feeling competitive. People will start finding faults in them. Why create trouble for those people? But their energy will be used."
Osho
From Death to Deathlessness, Chapter 3
Ma Yoga Lakshmi (video available)
Swami Bhrama Vedant
Swami Yoga Chinmaya
Others
There are more sanyassins who have attained but have kept it a secret, even after Osho left his physical body.
Enlightened Sannyasins - Self-declared
There are sanyassins who have reached to themselves, after Osho left the physical body.
Ma Mahadevi
Swami Rajneesh
Thyohar
Satya Prem
Others
Joke about declaring people enlightened
The Master is talking about his joke of declaring 21 people enlightened here. Also He describes how sannyasins can slip into enlightenment in a 25mile radius around him in the last passage.