The Tapeman is a brand of tape recorder used in Gravity Falls.
The Tapeman is first used by Soos in "Bottomless Pit!" during Dipper's "Voice Over" story; he used it to record Dipper's cracking voice and make a techno-remix out of it. Dipper then gets mad and takes it without even listening to the end of the song. It is seen again later when Dipper is discouraged because of the consequences of his new voice. He then decides to listen to the end of the song and realizes that his voice is what makes him unique.
The Tapeman makes another appearance in "Boyz Crazy." After Dipper figures out how Robbie's song is able to control Wendy, he uses it to record the hidden message in the song and decipher it. Later, Dipper uses the tape recorder to show Wendy the real message behind the song. After that, she shuns him for it, and he looks at the Tapeman and regrets what he has done.
The Tapeman has the look of an ordinary tape recorder, except that it has TAPEMAN written in white in the center.