Is there a potion of some sort in fallout 3 to revive dead people or animals

No. If someone dies, they're dead for good, unless you have a glitched game in which case the game might bring someone back from the dead
You ain't said what platform ya on, if you have the PC version, stand over the person or animal or maybe a insect, go in to console click on there corpse until it says there name up top of screen then just type resurrect