I've heard that there are suttas where the Buddha forbade people to call him by his given name. Which suttas are these?
This first occurred when he met the five ascetics after the enlightenment when they started calling him by his name Gotama before teaching his earliest discourse, Dhammacakkapavattana sutta.
Bhikkus, do not address me by the name Gotama nor as a friend. I have become a Perfect One, worthy of the great reverence.
Source: http://www.buddhanet.net/pdf_file/damachak.pdf page 56
Then, wandering by stages, I arrived at Varanasi, at the Deer Park in Isipatana, to where the group of five monks were staying. From afar they saw me coming and, on seeing me, made a pact with one another, (saying,) 'Friends, here comes Gotama the contemplative: living luxuriously, straying from his exertion, backsliding into abundance. He doesn't deserve to be bowed down to, to be greeted by standing up, or to have his robe & bowl received. Still, a seat should be set out; if he wants to, he can sit down.' But as I approached, they were unable to keep to their pact. One, standing up to greet me, received my robe & bowl. Another spread out a seat. Another set out water for washing my feet. However, they addressed me by name and as 'friend.'
So I said to them, 'Don't address the Tathagata by name and as "friend."