/ktavatu / क्तवतु

The /kRt affix ktavatu forms the "past active participle". These are fakeverbs that show the doer, unlike the /kta-nouns.

These are mostly used as if they were the main verb of a past sentence —

kRtavAn कृतवान् "he made something", "he made" — see **hanumAn हनुमान् for the An आन्
kumbhaG kRtavAn कुम्भं कृतवान् "he made a pot"

kRSNaH kumbhaG kRtavAn कृष्णः कुम्भं कृतवान् "Krishna made a pot"

dru द्रु + /ktavatu → !**drutavat- द्रुतवत्

**drutavat- द्रुतवत् m + /su → !**drutavAn द्रुतवान् m "ran", same steps as **hanumAn हनुमान्

**drutavat- द्रुतवत् + /GI + /su → !**drutavatI द्रुतवती f "ran"

But sometimes they can work like descriptives. So if it's a simple sentence —

uktavAn vibhISaNaH उक्तवान्विभीषणः "Vibheeshana said"

but the same two words will mean "vibhISaNa विभीषण who had said" in a more complex sentence —

suniviSTaM hitaM vAkyam uktavantaM vibhISaNam | abravId rAvaNaH ...
"to vibhISaNa , who had said... | rAvana replied ... "

The ending of the /ktavatu word shows the doer.