Ivan Wexler (better known as Blind Ivan), is an antagonist in the show, Gravity Falls. He was head a group of people who keep the secrets of town a mystery and erase others's memories of the events by using an invention, created by Old Man McGucket that makes them forget.
In "Society of the Blind Eye" he is first seen when Lazy Susan witness the Gnomes trying take her pie when she was grabbed by two of members
when Dipper, Mabel, Soos, Wendy and McGucket seek in their the museum they find the hidden meeting place of the members of the Blind Eye and seen Blind Ivan with the others when the erase Lazy Susan's memory of what she had seen before sending it away.
After the Pines twins, Wendy and Soos weir captured by the Society, Blind Ivan attends to make them forgot everything they've seen in the summer however McGucket comes to recuse, Ivan tries once again to erase Dipper and his friends' minds only for McGucket to get in the way as the invention had no a effect on him McGucket knocks Blind Ivan out cold, he along with the other society members are tied up, he along with the rest the society get their memories wiped by Dipper, after he set the gizmo to Society of the Blind Eye and blasted both Blind Ivan and all of the other members. however he ended up forgetting so much even who he was, but Mable made him belief that his name is Toot-Toot Mcbumbersnazzle and was a banjo player.
Ivan thinking who he was then leave while playing the banjo and singing "My is Toot-Toot".
In "The Love God" Blind Ivan could be seen walk in the crowd at the carnival while carrying his banjo, hinting he still doesn't remember who he is.
In "Weirdmageddon Part 1" the gearshift in Bill Cipher's car that he summons, strangely resembled Ivan's head, however it's unknown whether if this was the real Blind Ivan turned into an auto part or not.