One's Father, Middle-Aged Man, Father
noun
One's parent father is simply just one's father. Note that 親父 has a masculine and somewhat vulgar tone to it. It can refer to your own dad, someone else's, or a middle-aged man you're friendly with. When not talking about your own father, you'll want to add a さん at the end, making it 親父さん.
おやじ
The reading for this is unfortunately a bit of an exception. 親 uses the kun'yomi おや, and 父 uses the じ reading which you learned with 叔父. You've learned all these readings before, so as long as you remember them, you're good to go. If you don't, check out the mnemonics for these readings on their vocabularies' pages!
お前の親父さん、元気？
How's your dad?
あのヒゲ親父、ホント頑固なんだから。
That bearded dude is really stubborn.
俺は小さい頃から、親父の背中を見て育った。
I grew up watching my dad's back from a young age.